Add custom appendTo method.

In an internal application we are writing, the body tag is `position: fixed;` and we have a div inside of this that has overflow and scrolls. This fact breaks some things with positioning with jquery-minical which is what I would much rather use, over jquery-ui as we have had many issues with that as well.

This patch allows for a function to be defined that will append the minical wherever the result of that function is. I also wrote a couple tests for it. 

I noticed one of the tests is broken though and it was broken before I made my changes. I am not entirely certain what feature the test is testing, so I did not fix it. Let me know what else you think needs to happen to this before you pull it in.