* add some more RA-specific errors. add some doc to that effect.
* add some more RA-specific errors. add some doc to that effect.

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