* Use SILENCED_SYSTEM_CHECKS warning instead of test runner hack to
  avoid the warning about a change in default test runners
* Conditionally use south in the demo settings
* Add native migrations and app configs for forked apps

New style migrations created with the helper script. Now doesn't detect
any more changes after this set has been applied.

This change might need to be re-applied if more migrations get added
before this PR is merged into master.

More changes need to be done regarding migrations; this commit just
moves them out of the way so that Django doesn't pick them up.

This is probably a breaking change for most people as the migration
history for the order app has been rewritten.  It will take some
fiddling around with south to get your system back in order.

This change is required though as we need to break the links between the
apps.

The initial one is for the releases/0.1 branch - any others are to
handle changes in the 0.2 branch.