Postgres doesn't like it if you use 0 as the default for a booleanfield
previous migrations already create these columns so we don't need to create them again

postgres doesn’t like it if we try to add a column that already exists
the profile app has a dependency on webresponse already existing
the search app has a dependency on the profile already existing
postgres doesn't like it if we try to alter a time field to an integer field. better to just drop it and add it again.
remove the check to see if we're running on Heroku and remove South
clean up Heroku docs

apparently Heroku now detects a Django app and makes a database
automatically, so a separate step is not needed.
Merge pull request #184 from natea/herokudocs

Clean up the Heroku docs and fix PostgreSQL South migration issues

Huge thanks to Nate Aune (@natea) for addressing this at the sprint on Jan 4!