fix(tooltip): Transcludes contents to allow dynamic selector text

A dynamic selector did not work as the contents of the directive element
were not transcluded. This fix adds transclusion through a new directive
controller method. It also includes a new test for this case (through an
ngRepeat) as well as a modified demo to show this use case.

My apologies for the earlier PR I closed. The bug fix was correct, but the test was useless. This new PR contains the better test.

Closes #69