Add new UserOrganizationClaimer service

The service extract the business logic to request status and promote users to be admin to given organizations
Add UserOrganizationClaimer spec
Add User#request_admin_status
Fix User#request_admin_status add old code instead of update_attributes
Refactor: UsersController spec

Stub the nonadmin request_admin_status call only in a fixed context
Refactor: UserOrganizationClaimer

To fix bug inside promoting users to be admin
Fix UserOrganizationClaimer#call add correct logic
merging jon and rafael's pull request
Merge branch 'develop' of https://github.com/tansaku/LocalSupport into develop