Add functions to migrate roles

Add function migrate_role() for migration of single role.
Add function migrate_roles() for bulk migration of roles.
Add mapping of resource type 'role' to funciton migrate_roles().
Add a list of built-in roles

This list should be used to validate role names when moving about
roles.
Add role assignment creation to migrate_user() function

Same roles as in the source cloud are assigned to user in the
destination cloud.
Add roles to setup function

Now test roles are prepared in the sourcecloud when user calls
the script with 'setup' subcommand
Merge branch 'role-migration'