The patch does the following:
-Adds an issue_opened and issue_status field in both Comment (for Diffs) and ScreenshotComment.
-Adds a BaseComment resource for DiffComment and ScreenshotComment resources to inherit from, which allows for changing Issue status
-Adds a checkbox to the comment dialog to open an issue
-Adds UI for displaying (and for review request submitters, manipulating) Issue statuses.

Added some WebAPI tests to check issue_opened/status logic.  All tests pass.