Take a path argument

- Set the location of your prod db dump
Allow test db to be created

- Grant create to stagecraft user so it can create test db (thus run unit tests!)
Fixes to allow `convert-db.sh` to run

- asks for path to temporary db dump
- stops collectd to ensure we don't get port conflict errors
- assumes dump is gzipped (the fabric task to take down a copy of the live db defaults to a .gz file)
restart collectd
Add README to help with importing live db workflow
Remove legacy comments
Merge pull request #239 from alphagov/add_convert_script

Add script to help import production data to developement VM