Improved usage message of sip_settings script

Ignore-this: fd6dac72f515227012ca9939991b5336

darcs-hash:20090723110539-1e3d8-088cb46556dff1aa861d5c2063e426f354032f78
Modified MSRPChat and MSRPDesktop to conform to IMediaStream

Ignore-this: 37ed6e54763d84d63c3ccbd5163f21ad

darcs-hash:20090723133217-1e3d8-479dd494545b620747fe643d71b1192a6a59ea3d