Query and report Xrootd sitenames.
Revert back to IPAuto set of rules - less aggressive than IPAll, but still allows IPv6.
Record a warning anytime the xrootd client switches sites.

This aims to reduce the amount of logging that gets reported to
the user - likely the oonly time Xrootd will report anything at all
is when it is running against a global redirector.
Merge branch 'from-CMSSW_7_3_DEVEL_X_2014-11-05-1400' into xrootd-sitename

Conflicts:
	Utilities/XrdAdaptor/src/XrdRequestManager.cc
Merge pull request #6228 from bbockelm/xrootd-sitename

Xrootd sitename improvements