add configuration for connection timeout.
Allows users to control cookies by NSURLConnection API.
Improve the performance of data transmission.

1.Merge small packets.
2.Add the configuration of  TCP_NODELAY.
Revert "Improve the performance of data transmission."

This reverts commit ccebbdb099f2c30d3d2fc18b882eeea08efad026.
Improve the log.
Re-add configuration of TCP_NODELAY, data transmission improvements

Partially restores commit ccebbdb099f2c30d3d2fc18b882eeea08efad026
Rename connectionTimeout to connectTimeout
Minor code style change
Add comment
Add support for multiple sessions per origin
Indicate session parallelism in protocol version header
Remove some stray debug logging
Temporarily add nil check to next in SPDYSessionPool
Add SPDYBypass request property
Also respect 'x-spdy-bypass' request header
Fix stray reference
Note experimental configuration options
Add session-initial ping
Clarification on negative timeout
Fix ping test