Merge pull request #11 from Tivix/changes

Changes from Dariusz to add 'try "mins" after failure' feature.
Version bump to 0.2.1.
New version adds RETRY_AFTER_FAILURE_MINS feature.
Fixed and put django-common-helpers>=0.3

Bumped up version also.
Merge branch 'master' into changes
Added some entry in README