Add SDP Parser.

Signed-off-by: Yunchao Chen <chenyc@marvell.com>
Merge branch 'master' of https://github.com/YunchaoChen/rtsp

* 'master' of https://github.com/YunchaoChen/rtsp:
  Add rtsp module, ongoing.

Conflicts:
	.gitignore
	main.c
	rtsp.c
	rtsp.h
	sdp.h