pjsip: add frame buffer renderer device

Ignore-this: 928038d679a3b52aac9f7857c3660a33

darcs-hash:20140827143255-56b4d-9e9a721330823cebd5e3789ea624a541f10ce496
pjsip: add log if video converter is used

Ignore-this: 8857be43ef828d00871fdbd9843a7250

darcs-hash:20140827143338-56b4d-80f3253f1f5c43379a70ddc4f3448df2bb9b7790
pjsip: update to revision 4904

Ignore-this: 71a0d27ec9b6eba65e9c3c25e4464a18

darcs-hash:20140827143514-56b4d-f63234ad8361c68b03c41251bc232ddece614922