Fix error in parsing SIP registry strings from ASTdb.

It was essentially an off-by-one error. The easiest way
to fix this was to use the handy-dandy AST_NONSTANDARD_RAW_ARGS
macro to parse the pieces of the registration string out. Tested
and it works wonderfully.



git-svn-id: https://origsvn.digium.com/svn/asterisk/trunk@275385 65c4cc65-6c06-0410-ace0-fbb531ad65f3