Made TodoItem setters protected.
Added indexLabel, close #154
Merge branch 'staging' into dat/model
Merge pull request #155 from cs2103aug2014-w13-1c/jin/gui

Added indexLabel, close #154
Removed filtering capabilities from model. Passing filtering to TaskController.
Merge branch 'staging' into dat/model
Merge remote-tracking branch 'origin/staging' into jolly/gui