pjsip: remove unneeded files

Ignore-this: e096c21b1f2a89838521c947817b01c4

darcs-hash:20140911101830-56b4d-c1e8dd9e408aa9dc1c4a963953cc0590c2efba43
Fix race conditions when handling remote proposals

Ignore-this: bdacd566d8c9d400437366bea2b00293

darcs-hash:20140911141524-56b4d-12a9ada1bf0b2bb0de06f8f3ff960f285bf534f6
Fix race conditions when handling remote proposal requests

Ignore-this: 2e804c53a8b0dda00484cae13a97a8c5

darcs-hash:20140911151039-56b4d-c27772ace443701fb7ae4d2df30905ca66010a95