change the IPHONEOS_DEPLOYMENT_TARGET to 5.0 (from 4.0) so we can use weak references.
replace an __unsafe_unretained reference in SpdyPersistentUrl with a __weak one.
changes to SpdySession.m:

 - don't invalidate the socket after sending connectionFailed: (connectionFailed: does it for us)
 - add some debugging around added and removed streams