965 & 966 read only and editor permission fixes

closes #965
closes #966

The unresolved issues in the two are:
 - Downloading data and form allowed for read only project (in discussion on #965)
- Starring projects allowed for both roles (in discussion on #965)
- The enketo login/authentication issues for users with permissions to submit data is blocked by https://github.com/onaio/onadata/issues/403 will create an issues here to track this.