Fix error with assigning a badge to another user

Since the API got locked down by Authentication users only have
access to their own resources and as a result the UI cannot pull
down a user object for any user other than the currently logged in
user. Fixed this by adding a new route for assigning a badge by email
instead of user id. Part of #521
Merge branch 'develop' of gitlab.solas.uni.me:solas-match into develop