Created custom error SbError which inherits from JS Error.
Modified each AuthRule to user SbError
SbError API changes.
Added error msgs on the client side for auth errors.
Added handleAuthErrors.js to repo.
Error message improvements for auth-client
Removed redundant code in queryAuth.
Call Error superclass inside SbError
* Also removed superuser as a required role in errors thrown.
Authorizer: transition roles & types for 'join'.
Schema change for admitExpelAuth
Admit/Expel & Join/Part refactor + test cases
Test cases for admitExpel + some auth bugs fixed
Merge pull request #166 from scrollback/descriptiveErrors

Descriptive errors