disable cascade  delete as it deletes the versions object as well as the versions
Add details as to why a User may not exist
Add colspan
test that on_delete preserves User Revisions
removing helper text per comment
changed to &mdash to avoid the need to create new translations
Merge pull request #290 from daaray/master

[289] Preserve deleted User revisions
Derive pk column name dynamically for Users.User
table in initial migration.
Merge pull request #301 from aivins/master

Derive pk column name dynamically for Users.User table in initial migration
Update diffs.rst

Fix the reversion get method.
Merge pull request #302 from kzjeef/patch-1

Fix the reversion get method.
refs https://github.com/etianen/django-reversion/issues/307 replace sys.exit() with simple return
Merge pull request #308 from tongwang/master

refs https://github.com/etianen/django-reversion/issues/307 replace sys....
Bumping for 1.8.1 release
Testing more versions of Django
Updating docs for 1.8.1
Update docs for adding meta data
Merge pull request #313 from dhoffman34/master

Update docs for adding meta data
Add simplified Chinese translation.
Add simplified Chinese translation.