Refactor remaining resource methods

Implements instance methods for create/update/delete operations on resource classes and adds to/from dictionary methods
Update views to use new resource methods
Fix comment formatting
Pass access_token to updates if supplied
Add resource classes for File metadata and Attachment management
Add avatar file field to profile form and change encoding to multipart form
Add avatar upload processing to profile update view
Update all templates to use new avatar attribute on profiles
Add avatar attribute to Profile resource
Fix bug where microcosm.most_recent_update was being assigned to parent microcosm
Fix a couple of regressions in events
Update profile view/edit to reflect API changes for avatar
Merge pull request #72 from mattcottingham/avatars

Replace user profile gravatar with uploadable avatars
Change profile avatar field to ImageField and validate the upload size
Lat/Lon and bounding box are optional on events returned from API
Fix event form to so that it can be populated from an event instance without lat/lon and bounding box
Formatting
Initialise riemann client with host parameter and use UDP
Parameterise riemann host and remove unused persona test data
Add basic timing middleware which reports to riemann