feat(date): new dateFormatter helper

Factor out the date formatting handling into a new service `dateFormatter`.
While the default implementation uses angular's dateFilter and $locale, custom
implementations may use other libraries, e.g. [moment](http://momentjs.com/).

BREAKING CHANGE: If you include angular-strap files individually (from the `dist/modules`
directory) than `dist/modules/date-formatter.js` is now required to use the date/time
pickers.
fix(docs): add new date-formatter.js helper to docs

The new $dateFormatter helper service was missing from the docs index.html page.
test(tooltip): cleanup injection
fix(scrollspy): fix IE9 error when clicking scrollspy target element
chore(affix): revert some IE9 patches following #1230
test(tooltip): add custom-template $http tests
chore(tooltip): cleanup tests
feat(tooltip,modal): reuse fetchTemplate promises (fixes #1301)
chore(tooltip,modal): cleanup
docs(tabs): improve tab documentation for animations
docs(affix): remove animation option references from affix docs
test(timepicker): add tests for keyboard selection
fix(timepicker): keep correct time part selection when using keyboard to select time

When the key press handling changes the time value, we need to recalculate the position of the date parts to select after updating the time value.
fix(affix): revert to $affix reference in $onResize event handler

The affix $onResize event handler was throwing an error when using 'this' to refer to $affix
docs(tab): switch SASS with LESS reference
docs(hacking): add note regarding bower install
chore(release): cut the v2.1.4 release
chore(npm): add @vmlf01 as a contributor
chore(npm): update devDeps
feat(tooltip): add ability to auto position tooltip

Add ability for tooltip (and any dependent directives) to be auto
positioned.  Placement option has been enhanced to look for `auto`.  If
present, tooltip will try to position itself in viewport.  A preferred
placement can also be specified by appending desired placement to auto.
Tested against Win 7 Chrome, Firefox, IE 9-11.