Updated the user controller to use user object instead of strings.
Changed code in all controllers to retrieve context instead of activity.
Changed the name of cntrl to their respective controller names for clarification.
Removed all non-aggregation, composition and inheritance relationships
Merge branch 'master' of https://github.com/CMPUT301W14T3/Group-Project
Rearranged UML chart with emphasis on smaller size, readability and compactedness