Fix parsing SMSSRC for SMS messages

The parser for SMS messages would incorrectly parse out the from number.
The parsing would incorrectly start scanning for the from number at the
same index as the first double quote ("); this would inadvertently cause
it to treat the first double quote as the terminating double quote for
the from number as well.

The SMSSRC should now populate correctly.

(closes issue ASTERISK-16822)
Reported by: menschentier
Tested by: Jonas Falck
patches:
 fixSMSSRC.patch uploaded by jonax (license 6320)

(closes issue ASTERISK-19153)
Reported by: Panos Gkikakis
patches:
  sms-sender-fix.diff uploaded by roeften (license 5884)  



git-svn-id: http://svn.asterisk.org/svn/asterisk/branches/1.8@379178 f38db490-d61c-443f-a65b-d21fe96a405b