Added functionality for changing a users role. Also made changes to @get
users/myrole and added a new id column to the authorities table.

 Logic and security is mostly found in userResource which is different
than the usual pattern
of just using annotations on the Service level interface.  The reason
for this is that the logic of who was allowed to do what was too
complicated to easily do via annotations.
Merge branch 'master' of github.com:DataAnalyticsinStudentHands/VolunteerManagementBackend