Expect date objects rather than strings
Bump backdrop-collector version to 0.0.5
Add start and end dates to collect.py

Allows data to be backfilled.
Remove run.py in favour of collect.py

Also, update the README to reflect that.
Merge pull request #11 from alphagov/collect-by-date

Collect by date
Make travis use run_tests.sh like CI
Fix PEP8 violation
Merge pull request #12 from alphagov/fix-travis

Fix travis