Improve statement tooltip sizing and positioning

Fixes #2189. There was two issues in that ticket…

1. Statement tooltips for cards on the far right had a smaller width
2. Statement tooltips for cards at the bottom were being cut off in the viewport

This PR fixes both issues…

1. Tooltips have a fixed size now, which is a bit smaller than the first release
2. Tipr now detects if a tooltip will be occluded before making it appear. If it will be occluded it will force the position to the “top” mode so the tooltip appears at the top of the parent element instead of the bottom

See https://github.com/eswat/tipr/tree/master for non-minified source and changes.

![screen shot 2014-03-28 at 4 43 23 pm](https://cloud.githubusercontent.com/assets/65468/2555049/ac880426-b6b9-11e3-857d-7e288df1ad69.png)