SFT support fixes - improve error checking, include .sftbad extensions
Adds fallback to parsing diskcache as PFN list on read failure. Closes #12 (as a workaround).
gwrucio_registrar2 robustness improvements. Deployment-ready. Penultimate release before deprecation of old registrar.
Support non-deterministic RSEs and more literal deterministic lfn2pfn algorithms