Added backend interface. Moved PerfBackend over. Generalize perfbackend.
Added perfbackend/config.py to gitignore.
Folded in PerfConvert, also moved away from orm to core sqlalchemy for perf database.
Added perfconvert config file to .gitignore.
Added tests to backend. Reworked perf and sgd backends to implement backend_interface. Switched perfconvert to work directly from sgdbackend.
Finished merging in perf.
All tests running for both sgdbackend and perfbackend. Ready to merge back.