Add roles to the proxy

DagKnows supports role based access control. Every user has a unique role. Users cannot have multiple roles. The roles are assigned when the user is created in the DagKnows application. Currently DagKnows supports the following roles:

1. supremo : This is superuser. There can be only one super-user. This is relevant only if you are using local DagKnows app.
2. admin: Admin who has pretty much all the privileges as superuser
3. techrep: This is a normal user.