updated README for consistency

The documentation section has all sentences ending with a period except for number 3. I've added the period to make the section more consistent with the rest of the document.
Prevent 'cannot read' exception

On Android (4.4.4) I'm getting "Cannot read property 'options' of null" each time, 100% reproducible.
This small check will not hurt anyone but will prevent unhandled exception error.
chore(): remove unused platform css
chore(): cleanup unused variables
refactor(scrollBar): rAF scrollbar transitions

Only make changes to the scrollbar element’s style when there is a
change, and use requestAnimationFrame when there is a change.
refactor(clickBlock): transform css for click block

Use transform/opacity CSS properties to show and hide the click block
element, and use requestAnimationFrame for the DOM changes. This is
easier for the GPU to use transform/opacity properties instead of the
display property, and also reduces any potential reflows.
refactor(): navigation improvements, Angular 1.3

#### Refactor:

* **Navigation:** Refactored navigation for improved performance,
reduce DOM manipulations, increase transition FPS, cached views,
smoother transitions, platform specific transitions with added
configurable controls for transition animation and direction.
* **Cached Views:** Previously as a user navigated an app, each leaving
view’s element and scope would be destroyed. If the same view was
accessed again then the app would have to recreate the element. Views
can now be cached to improve performance. When a view is navigated away
from, its element is left in the DOM, and its scope is disconnected
from the cycle. When navigating to a view which is already cached, its
scope is reconnected, and the existing element which was left in the
DOM becomes the active view. This also allows for scroll position of
previous views to be maintained (without skippy jumps). Config
variables can be used to disable view caching (set to 0), or change the
maximum number of views to cache.
* **Angular v1.3:** Upgraded Ionic’s to work with Angular v1.3. In
general Ionic just works with the upgrade, but the required change was
that animations in v1.3 uses promise, whereas in v1.2 animations used
callbacks.

#### Features:

* **Platform Specific Transitions:** Transitions between views now
default to the transition style appropriate for each platform. For
example, iOS will move forward by transitioning the entering view from
right to center, and the leaving view from center to left. However,
Android will transition with the entering view going from bottom to
center, covering the previous view, which remains stationary. Platform
transitions are automatically applied by default, but config variables
and custom CSS allows these defaults to be easily overridden.
* **Override Transition Type and Direction:** As a user navigates the
app, Ionic automatically applies the appropriate transition type for
the platform, and the direction the user is navigating. However, both
can be overridden in numerous ways: config variable, view attribute,
stateProvider property, or attribute on the button/link that initiated
the transition.
* **enable-menu-with-back-views:** The `enable-menu-with-back-views`
attribute determines if the side menu is enabled when the back button
is showing. When set to `false`, any buttons/links with the
`menuToggle` directive will be hidden, and the user cannot swipe to
open the menu. When going back to the root page of the side menu (the
page without a back button visible), then any menuToggle buttons will
show again, and menus will be enabled again.
* **menuClose:** Closes a side menu which is currently opened.
Additionally, the menuClose directive will now cause transitions to not
animate between views while the menu is being closed.
* **ionNavBackButton:** The back button icon and text will
automatically update to platform config defaults, such as adjusting to
the platform back icon. To take advantage of this, the
`ionNavBackButton` directive now should be empty, such as
`<ion-nav-back-button></ion-nav-back-button>`. The back button can
still be fully customized like it could before, but without any inner
content it knows to style using platform configs.
* **navBar button primary/secondary sides:** Primary and secondary
sides are now the recommended values for the `side` attribute, such as
`<ion-nav-buttons side="primary">`. Primary buttons generally map to
the left side of the header, and secondary buttons are generally on the
right side. However, their exact locations are platform specific. For
example, in iOS the primary buttons are on the far left of the header,
and secondary buttons are on the far right, with the header title
centered between them. For Android however, both groups of buttons are
on the far right of the header, with the header title aligned left.
Recommendation is to always use `primary` and `secondary` so buttons
correctly map to the side familiar to users of a platform. However, in
cases where buttons should always be on an exact side, both `left` and
`right` sides are still available.
* **navDirection:** An attribute directive that sets the direction
which the nav view transition should animate.
* **navTransition:** An attribute directive that sets the transition
type which the nav view transition should use when it animates. Using
`none` will disable an animation.

#### Breaking Changes:

* **Animation CSS:** The CSS for view transitions have changed. This is
a breaking change only if Ionic apps had customized Ionic’s animation
CSS.
* **$ionicPlatformDefaults:** Platform config variables are no longer
in the $ionicPlatformDefaults constant, but within `$ionicConfig`.
* **$ionicViewService:** In the navigation refactoring,
$ionicViewService was split up into two factories, `$ionicViewSwitcher`
and `$ionicHistory`. The `$ionicHistory` is largely what
`$ionicViewService`, but between the two factories there is a better
separation of concerns for improved testing.
* **navClear:** The navClear directive was created to do what the new
side menu `enable-menu-with-back-views` attribute accomplishes.
Additionally, the new `navTransition` and `navDirection` directives are
more useful and granular than the navClear directive.
* **scrollView.rememberScrollPosition:** This method has been removed
since it is no longer needed with cached views.

#### Deprecated:

* **ionView.title:** The `ionView` directive used the `title`
attribute, but this can cause the tooltip to show up on desktop
browsers. The `title` attribute will still work for backwards
compatibility, but we now recommend using `view-title`, such as
`<ion-view view-title=”My Title”>`.
* **ionNavView animation attribute removed:** The animation attribute
is no longer used for nav views. Instead use `$ionicConfig`.
* **ionNavBar animation attribute removed:** The animation attribute is
no longer used for nav bars. Instead use `$ionicConfig`.
fix(nav): prevent nav-bar flicker w/ no animation
chore(jscs): add JSCS to work toward syntax parity with angular
fix(nav): correct element structure for nav-vew

Ensure that the entering view template is contained by one element, and
that one element has the `pane` class.
style(*): jscs linter updates to nav improvements
chore(jscs): add gulp task for jscs
chore(package.json): sort devDependencies
feat(goBack): add $ionicHistory.goBack()
docs(navBarDelegate): update available methods
fix(listView): unchecked null pointer
feat($ionicConfig): chaining config properties
refactor(colors): update default ionic colors
feat(menuClose): do not show next back button

When navigating to a view from a button/link with the `menuClose`
attribute directive, the back button should not show for the next view.
chore(viewContainer): add position absolute