A Start at Speeding Up the Expert Dashboard Page Along With Some Code Cleanup

Still a work in progress.
Speed Up Tags Query and Calculations for Expert Dashboard
Moved Tag Scope to Class Method
Using Memcache to Speed Up Processing of the Two Most Time Consuming Queries on the Expert Dashboard
Only Store Number of Questions in Memcache Instead of Objects Themselves

A few other cleanup items included as well.
Do Not Allow New Comments for Private Questions
Keep Comment Count Accurate After AJAXed Comment Create
Handle Plurals Correctly
Merge branch 'speed_it_up'
Merge branch 'commenting_rules'