refactor(): add -gt- attrs, switch back to sm/md/lg

BREAKING CHANGE: the -phone, -tablet, -pc, and -tablet-landscape
attribute suffixes have been removed and replaced with -sm, -md, and -lg
attributes.

* hide-sm means hide only on small devices (phones).
* hide-md means hide only on medium devices (tablets)
* hide-lg means hide only on large devices (rotated tablets).

Additionally, three new attribute suffixes have been provided for more flexibility:

* hide-gt-sm means hide on devices with size greater than small
 (bigger than phones).
* hide-gt-md means hide on devices with size greater than medium
 (bigger than tablets)
* hide-gt-lg means hide on devices with size greater than large
 (bigger than rotated tablets).

See the [layout options
section](http://material.angularjs.org/#/layout/options)
of the website for more up-to-date information.
refactor(style): this restyles parts of the site's layout

enhance(style): added angular logo and switched to red theme

enhance(style): updated toolbar colors for red theme

enhance(ripple): adds a minimal timeout to make sure that updates are complete before creating ripple

feat(theming): adds md-theme-levels directive

enhance(nav): sets focus state for nav items
docs(): layout doc changes
fix(ripple): fixes bug with vertical ripple alignment

Closes #725. Closes #736.

Switches FAB ripples back to non-centered.
Resolves vertical alignment issue.
Cleans up code tabbing in ripple.js.
Adds function comments in ripple.js.
enhance(ripple): adds new ripple styles for tabs enhance(tabs): adds grow/shrink effect during ink-bar animation
fix(ripple): fixes ripple bug with checkboxes in lists

Reduces the ripple size slightly to prevent scrollbars from showing up in list items.  Closes #679.
fix(button): adds override for transitions on ng-hide

Closes #678.
enhance(ripple): removes important flag on ng-hide override
fix(sidenav): use flex display when opened

Closes #737.
amend(layout): fix hide rules not working
feat(mdBottomSheet): add escape to close functionality
chore(docs): update layout attrs to new format
fix(layout): add [flex-{sm,md,etc}] attr for 100% flex on screen size

Closes #706. Closes #707.
amend(flex): use flex: 1 instead of complicated width property
docs(guidelines): update developer guidelines and READMEs
docs(): polish
perf(tabs): replaces left/width animation with transform
enhance(demo): re-added :focus state to demo tabs
enhance(tabs): updates timing for tab animations
amend(ripple): undoes previous commit