Restart workers when they have handled 5000 requests
Add 'mark as read' metabar module and API resource

Uses the /profiles/read path to mark either the entire
site or a single microcosm as read.
Merge pull request #233 from mattcottingham/wip-mark-read

Add 'mark as read' to metabar
Use hasattr instead of expecting AttributeError
Reconstruct API requests in error views to fetch site/profile info
Refactor API exception handling in core views
Handle API exceptions in microcosm views, instead of using exception_handler
Handle API exceptions directly in conversations/views
Use module-level objects where possible in conversations/views
Handle API exceptions directly in huddle views
Use module-level objects in for huddle views
Add respond_with_error for surfacing APIExceptions to user
Use respond_with_error for most APIExceptions
Fixed unread indicators in search results
Handle APIExceptions directly in comments/views
Create a separate error view for handling expired logins
Use module-level objects where possible in comments
Remove unused import
Handle APIExceptions directly in event views
Use module-level objects in event views