SD-759 : Enable etags on backend

In order to enable tags on settings.py change IF_MATCH to True.
All tests pass after the etag is enabled.
SD-759: Enable etags on backend

Enabled etags
SD-759 - Enable etags on backend

Disable etags until the frontend is updated
Merge pull request #291 from ioanpocol/master

SD-759 : Enable etags on backend