Added media initiation and rtp lib

Msi protocol is now in it's alpha stage since it supports (not yet fully tested nor in its final form) most of the features for tox requirements. Couple of rtp changes/fixes and it's well tested at this point ( I'm not saying that there are certainly no bugs but most of them are fixed ). If you notice any bugs please report them here or on irc channel: #tox-dev at freenode.net.