Split up wagtailadmin tests
Added wagtailadmin account management tests
These test the following:
 - Users can login and logout
 - Logged in users are redirected to dashboard (not implemented yet #25)
 - Account section works and users can change their password
 - The password reset functionality works
Added tests for unpublish view
Added permission checks to page views
Added tests for approve/reject moderation views
Added error tests for approve/moderation views
Improvements to search view tests
Unit tests for snippets views
Added tests for fixtree command
Fixed invalid numchild values in test fixtures
Added test for move_pages command
Added test for replace_text command
Removed unneeded import
Added tests for submitting pages to moderation
Added test for preview on edit
Added test for preview on create
Added test for content_type_use
Added test for preview for moderation
Added missing template
Added test for send email task