test(scope-helpers): add tests for tooltip and modal show/hide/toogle scope helpers
fix(modal): fix consecutive calls to show or hide methods

Calling show two times in a row causes two modal elements to be added to the page and the references to the first one get lost.
Calling hide two times in a row causes an error the second time because the modal element does no longer exist.
test(tab): add tests for dynamically adding and removing tab panes
fix(tab): add support for removing tabs
fix(datepicker): fix startDate attribute with a date object