Updated README and installation instructions

Ignore-this: fb3ac315ffa01f5002159b551048b9ef

darcs-hash:20130808115351-56b4d-6d3fbd6775f49877fcd1c4f7f6ba99d44439610a
pjsip: Avoid compiling pjsua-lib

Ignore-this: 9dffe0324f4233492c6f8d59915717b2

darcs-hash:20130808120827-56b4d-c535058c737452d00238fee5cc32e7404bb29c35