Changed users_role to user_role

Changed all instances of users_role to user_role for more consistent
naming.
Changed users to user except for class name

I used this regex to find: ([uU][sS][eE][rR])([sS])([^ "][^p])
This regex to replace: \1\3
Added validation for badge no event

Added a validation to the registration validation view to find users who
have badges but didn't register for anything else. Also refactored the
sub-view into a separate view script. Updated the rebuild_database.sql
file accordingly.