add [SPDY connectionStateString:] and rename
[SPDY connStatusString:] to [SPDY networkStatusString]
add a bunch of logging to SpdySession to help debug some reconnect issues
changes for SpdyPersistentUrl:

 - track renaming of [SPDY connStatusString:]
 - always send a ping on radio access change (regardless of wifi)
 - add some more debugging