[#873] Updated API calls to change password, details and request organisations

The API calls for changing a password, or details and for requesting organisations were only working for superusers. These have been adjusted now so that any authenticated user can perform these actions.
[#873] Some small styling fixes
Merge pull request #880 from akvo/feature/873_v3_my_details

[#873] Updated API calls to change password, details and request organisations