feat(tooltip,popover): logic moved to $tooltip svc

Popover and tooltip directive creation is now performed through the help
of the `$tooltip` service that manages all aspects of directive
creation and management based on only the name of the component and
their default triggers.

The tooltip and popover sub-directives and their templates were
refactored to use common scope variables that the new service can
provide, yielding even greater flexibility.

Animation is now enabled by default.

Lastly, the `$tooltipProvider` has been established to allow setting
default global options for the tooltip and popover, but these features
are not yet public as the API is sure to change drastically as we flesh
out which global options to allow. But the framework is in place as this
was a logical time to incorporate it.