Add rnastructure

This is a set of generally useful libraries for dealing with rna structure. I'm
using it go get chain breaks right now. It will also be used for unit id
translation later.
Working version of chain breaks loader

This can load chain breaks and store them in the database easily. It uses code
in rnastructure to find the breaks and then stores them as needed.
Check if breaks exist and setup for better logging

Later we use several loggers so this setups for that a bit. In addition, we
should not keep writing breaks if they already exist. This prevents that. We
should also probably have some sort of unique constraints in the database.
Update to newer version
Use unit id converters and assume AU

We are assuming that we should use the AU as the type instead of BA?. This is
flawed but will work for the basic stuff now.
Add smoke test for chain breaks

Simple and not terribly effective test.