feat(alert): add WAI-ARIA markup

Closes #1806
chore(demo): fix fork button width

Closes #1805
fix(datepicker): `Today` button should not set time

Fixes #1726
Closes #1808
fix(progressbar): number filter in bar template and only for percent

Closes #1807
refactor(dropdown): remove isolated scope

Closes #1818
feat(typeahead): add WAI-ARIA markup

Closes #1814
refactor(accordion): transclude function in compile is deprecated.

Closes #1789
refactor(carousel): use `track by` in template

Closes #1723
fix(datepicker): mark input field as invalid if the date is invalid

Closes #1845
fix(datepicker): rename `dateFormat` to `datepickerPopup` in datepickerPopupConfig

Closes #1810
fix(dropdown): unbind toggle element event on scope destroy

Also, change the way disabled dropdownToggle is read from `attrs` instead of element property.

Closes #1867
Closes #1870
fix(datepicker): DatepickerPopupConfig tests