Add ...-append-to-container for components such as tooltip

[omacarena]

You should be able to set the means (maybe selector) of defining the parent element which will act as a container.

For example you have an element triggering the tooltip, which is inside a position: absolute or position: relative element, thus showing the tooltip incorrectly.
On the other hand you want to style the scrollbar and you opt for another element to be used for scrolling in order to apply some fancy scrolling directive (eg: angular-perfect-scrollbar, ng-scrollbar, ...) or you just want to have a header or the remaining of the content to be scrollable using another element.
In this situation you cannot opt for using tooltip-append-to-body="true" because has overflow: hidden, thus leaving you with the option of adding the tooltip to another parent element that is suitable.

This functionality is implemented in other libraries as:

• Bootstrap - data-container - http://getbootstrap.com/javascript/#tooltips-options
• Angular-Strap - container - http://mgcrea.github.io/angular-strap/#/tooltips

It seems that there was an issue opened for this as [https://github.com//issues/139] but for simplicity sake ...-append-to-body was chosen which does not cover all aspects.

[wesleycho]

Feel free to open a PR - I'm immensely busy these days, and likely won't get around to it anytime soon myself.