refactor(view): use nextUid from angular to generate unique ids

Math.random() is unreliable, produces duplicates, and numbers can
overflow if you use them for long enough.
feat(content): remember scroll of previous page

`content` directive stores scroll in view page history.

The history is passed down through $viewContentLoaded event, which is
broadcasted by navView directive when it loads a page.
chore(build): automate release process
fix(ionicTouch): use ionic.tapElement
chore(build): remove commit msg hook
fix(navBar): Back button w/ text to use inner <i>
chore(build): more ci server automation
chore(travis): cleanup travis script echos
feat(tabs): clicking tab item again navigates to tab's home
chore(travis): codename, build version updates
chore(travis): update codename, cdn push fixes
chore(readme): update with download methods
fix(ionicView): erase saved scroll for a view on back
chore(travis): make "do-not-build-on-pull-request" work
feat(tabs): allow badges on tabbar via bound `badge` attr
chore(release): v0.9.23
update change log
fix(range): Update range for android 4.0-4.3
chore(travis): more robust release detection
chore(README): add note about commit conventions