fix($animate): update animate.enter() behaviour

In angular 1.3 $animate.enter() will now insert in the first position of the parent element when "after" is not specified. This change updates the tooltip and modal $animate.enter() calls to specify after as the last element of the parent. 

this is due to changes from: https://github.com/angular/angular.js/commit/1cb8584e8490ecdb1b410a8846c4478c6c2c0e53

this caused nested tooltips/modals to be inserted behind the old ones i.e when one modal opens another modal and neither has a container specified (or if they had the same container).