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(jscs): add gulp task for jscs
chore(package.json): sort devDependencies
removed duplicate $tabs-text-font-size
docs($ionicHistory): add docs
docs(loading): add missing documentation for passing scope

Closes #1982
docs(ionicCaching): enabling/disabling caching of views
docs(navView): update caching docs
fix(headerBar): view header bars stay under nav bars
refactor(transition): remove navBar.transition config
test(ionicConfig): update config tests
fix(SlideDrag) clears drag when list is scrolled or new drag starts

This also fixes the broken $ionicListDelegate.clearOptionButtons() method.

Makes lists feel more natural inline with iOS functionality and fixes issues
with using ion-option-buttons with collection repeat
chore(navBarController): deprecate methods w/ warnings
fix($ionicHistory): pop duplicate view registers
Merge pull request #2558 from mallzee/slide-drag-clear

fix(SlideDrag): clears drag when list is scrolled or new drag starts
fix(tabs): fix goToHistoryRoot
chore($ionicViewService): deprecate
refactor(uiRouter): updates for Angular v1.3
docs(ionicConfig): added navBar config