Merge pull request rdmorganiser#50 from rdmorganiser/0.9.0

0.9.0

fix tasks for invalid dates

fix project xml export

fix rollback

Merge pull request rdmorganiser#30 from rdmorganiser/test_mixins

Test mixins

fix for render_to_format title

upgrade to Django 1.11

Merge branch 'master' of github.com:rdmorganiser/rdmo

add cache documentation

fix export and import