[#902] Added User.get_short_name() for use in admin
Merge pull request #903 from akvo/feature/902_v3_admin

[#902] Added User.get_short_name() for use in admin
[#884 #905] Styling on registration complate page fixed
[#823] Updated 403, 404 and 500 pages
[#823] Approve user in user management table

The user management table now has the following logic:
- A green check is shown if an employment is not approved yet
- A red cross is shown if an employment is approved
- Nothing is shown if the (logged in) user is not connected to the organisation in the employment

Also, the user management link and page (and API calls) are only available to superusers, staff members, editors and organisation admins.
[#823] Missing trailing enter
[#905] Updated signal to send email when employment is created
[#780] First version of my projects page on MyRSR
[#780] My projects page in MyRSR

Added data to the my projects page, showing all projects (published and unpublished) of the organisations the user is connected to.
In addition, there are three 'action' links:
- View (always shown), points to project page
- Edit (only for superusers, etc), points to project admin
- (Un)publish (only for superusers, etc), points to publishingstatus admin
Merge pull request #911 from akvo/feature/780_my_projects

[#780] My projects page in MyRSR
[#884] Updated user approval process

It should be possible to request to join an organisation again, and emails wil be sent out when a user does so.
In addition, the user management page is updated;
- The logged in user is not shown in the table
- Only users of approved organisations (of the logged in user) are shown
- The permissions column has been removed, since we need to re-think permissions (read: implement object-level permissions)

Also, on the my details page, the organisation list shows when a user is not approved for an organisation.
[#781] Added media, actions and pagination to my updates page
Merge pull request #913 from akvo/feature/781_v3_my_updates

[#781] Added media, actions and pagination to my updates page
[#884] Updated 'approve' REST view and Modal title
[#884] Gulp fix for *.scss files
Merge pull request #907 from akvo/feature/884_v3_registration

[#823 #884 #905] Approve users and updated registration process
Merge pull request #916 from akvo/issue/909

[#909] Top nav is now responsive
Merge pull request #917 from akvo/issue/909

[#909] moved bac JS libraries from footer to head
[#909] Merged 'feature/rsr_v3' into branch