Add "My Comments" column in user's review requests listing

Review Request #3362 — Created Sept. 28, 2012 and submitted — Latest diff uploaded

Information

Review Board

Reviewers

"My Comments" column was unavailable as a column under a user's review
requests listing. Creating a variable storing an instance of the
MyCommentsColumn class inside the ReviewRequestDataGrid class fixes the
issue.

This fixes Issue #2163
Created a few comments and tested it in my browser manually