test(modal): Remove `ddescribe` in the $modal tests

The `ddescribe` is only executing the $modal tests. Removing it will allow
all other unit tests to run.

Fixes #2311.
chore(Gruntfile): add `grunt-ddescribe-iit` task to CI checks

This should prevent `ddescribe` and `iit` blocks in tests from being checked into the tree, as they
were in #2311.
fix(timepicker): Always pad the hours and minutes

The timepicker only padded the minutes and hours when the template first
loaded. The hours and minutes are now also padded when the model
changes.

Fixes #2314.