Fix reopening video device

Ignore-this: 7d516e843f90988323b14d2204379420

The video4linux backend is quite picky, so make sure we have closed the
previous camera before trying to open it again.

darcs-hash:20141023132253-56b4d-121e9d58f2a01fe3d45c143ef6c56b9d1a09cf93
pjsip: updated bundled PJSIP to revision 4961

Ignore-this: 65ebe7e8f64686c9b9c264cf71a97974

darcs-hash:20141117153258-56b4d-27c2280438687661aa342be84124103186884dda
Make sure a removed stream always has a connection line

Ignore-this: f59ffdd71401f15ee5c96b2eb12431f4

As weird as it sounds, removed streams (those with  port set to 0) also
need a c= line, if not present at the session level

darcs-hash:20141117160120-56b4d-4a23a7f756ea8d6159c3743fb343f515bae36200