Multisource bugfixes

From the latest round of testing:
1) Make sure the problematic server is logged if we fail during recovery.
2) Align all timeouts to the same default; make sure all Xrootd client timeouts are set.
3) Add recovered source to list of active sources; this prevents us from triggering an assert on having no active sources.

These are the last issues that large-scale CRAB3 testing has revealed.  I think we are ready to try a relval run on this branch.