ra_serf: Do a pass at documenting some ra_serf-internal functions.
ra_serf: Do a pass at documenting some ra_serf-internal functions.

* subversion/libsvn_ra_serf/ra_serf.h: Sprinkle a litle bit of docco...

jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion,jmckaskill/subversion