Merge pull request #73 from wdoekes/wjd-pua_min_expires_doc

pua.c sets int min_expires= 300, not 0 as documentation states.
- fixed overflow in parsing the content len value
  Reported by franklyfox on GITHUB
  Closing issue #78
- fixed double free when building insert fails (in buffered insert mode)
  Reported by Brett Nemeroff
Merge branch '1.9' of https://github.com/OpenSIPS/opensips into 1.9