Sets up paper_trail tracking in important models
and add conference_id to versions for storing conference_id
of conference related objects as metadata.This will help in querying
for versions related to conferences.
Fix issues with factories & event types initialization.Import paper_trail testing helpers
Fix bug: Creating an event creates a useless version with event update
Add revert and view changes features to revision history
The default colors in event_types and difficulty levels are in capital letters and the ones that comes from the color picker were not. Now colors are capitalized before saving the track, level or type. A rake task has also been created to capitalize color from old tracks, levels or types.
