Add conditional Formatting / annotation support

[buggtb]

Allow for annotations similar to comments in Google Docs that allow for Dimensions, Levels, Members, and cell segments to be annotated and commented upon.

Add server side capabilities for addressing/reading/writing annotations
Come up with a limited syntax for comments (some easy to use Wiki Markup language seems like a good target)
Display the "availability" of comments on the pivot table, and a detail pane (to the right) that can show comments as a stream (or details if clicked from the pivot table)