Auto build new tags when pushed.

Add tests for this and the stable version code.
Fix project editing
Confirm user exists
Fix project update form call
Dynamically discover requirements files
Initial parts of Bitbucket importing
Add automatic documentation type choosing
Add “basic” concept to builders, on basic imports.
Specific modeling for BB
Default to auto discovering of doc type
Add initial build signals
Auto build new tags when pushed.

Add tests for this and the stable version code.
Fix version arg
Merge branch 'add-build-signals' into project-onboard-improvements

Conflicts:
	readthedocs/projects/tasks.py
Fix failing privacy tests due to import wizard changes
Fix views tests using import form
Add project import tests

Adds wizard base class for testing wizard forms
Remove token passing
Fixes for project tests, change view backend naming
Handle generating pages config in mkdocs