Fix PageUserAdmin for custom user model.

Don't crash at startup if the custom user model has no first_name and
last_name fields.

The PageUserAdmin still won't actually work, so you'll have to subclass
it and change the fieldsets to include the fields that actually work, but
at least you can import it now.
Modify the custom user model to have fewer fields.

Allows us to test whether PageUserAdmin works or not.
Fix tests throwing another exception during teardown.

This conceals the original error that you actually want to fix.
Test against custom user model to trigger failures.
[requires.io] dependency update
[requires.io] dependency update
Implement more django 1.7 migration semantic
Recreate migrations with newer django version
Temporary requirements
Fix support for custom user models
Exclude MySQL/PY3/Django1.7 from test matrix
Fix test matrix
switch back to divio repositories for plugins
Update travis file
Fix travis file
Add test for #3338
Deepcopy fields definition in PageAdmin.get_form
PEP-8
refactored & fixed plugin signals
Fix unique constraint violation and UnicodeEncodeError in publisher_publish command