fix(dropdown): fix hide method to check if dropdown is open first
fix(datepicker): fix hide method to check if datepicker is open first
fix(timepicker): fix hide method to check if timepicker is open first
test(bsShow): add bsShow attribute tests
test(bsShow): add tests for bsShow attribute with string values
fix(bsShow): fix bsShow to support using "true" string to show element
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.