Fixing %(here)s in included configs, fixes #81

As we talked, we need to problem with %(here) to be fixed.
I kept my own hacky approach and fixed it without breaking unit tests.
However, maybe adding some tests for this feature would be nice.

Let me know if you can pull this.

Cheers
This code is parsing a config file, modifying it in memory, then writing it out to a temp file just so it can be read in again.  If there is something in our existing code forcing this kind of hack then we should fix it.  I would like to fix `%(here)s` for included configs but I think there must be a cleaner way we can do that.