Improvements to the signups API.
Merge branch 'master' of github.com:ucam-cl-dtg/urop-2014-ticking-ui

Conflicts:
	ETick/src/main/java/uk/ac/cam/cl/ticking/signups/TickSignups.java
Merge branch 'master' of github.com:ucam-cl-dtg/urop-2014-ticking-ui