Start new test factories using factory boy

These are intended to replace the old, hand-written ones - hence why
they are importable from the same module.

Will take some time to replace all the old ones though.
Merge old factoryboy factories into new module
Extend login/registration view

The new version has been extended to allow the success URLs and messages
to be easily customised.

We also now redirect staff members to the dashboard when they first
login.