Encoding headers can overrun the buffer.

Validate buffer size while encoding headers, and pass the NSError back
up the stack. If over 16K of headers are encoded, this will result
in the stream being closed.
Ensure connections can't be opened past the fire date of a connect timeout
Move all configuration onto a single dispatch queue
Feedback from last change.

Change error code and buffer size tweak.
Merge pull request #52 from kgoodier/encode-headers-crash

Encode headers crash
Update example
Merge pull request #55 from dkhamsing/patch-1

Update example
Remove whitespace
Return metadata information for failed requests.

Requests that got a response used to include some metadata information
in the response headers, such as version, stream id, and latency. This
change also includes that information when there is no response and an
NSError is being returned, by using the same header names as keys in
the userInfo member of NSError.

This change also removes the parallelism metadata, as it wasn't being
used and is available in the configuration.
Rename "SPDYMetadataRequestStreamId" to "SPDYMetadataStreamId".
Merge pull request #56 from kgoodier/metadata-for-errors-in-stream

Metadata for errors in stream
Merge branch 'metadata-for-errors-in-stream' into develop
Merge remote-tracking branch 'upstream/develop' into develop
Merge branch 'master' into develop
Add additional default HTTP headers to better mimic NSURLRequest's behavior.
Public "metadata" string constants style cleanup.
Additional comments about default HTTP request headers.
Merge pull request #58 from kgoodier/add-http-headers

Add default HTTP headers
Split build into platform-specific frameworks
Merge pull request #57 from kgoodier/metadata-style-cleanup

Metadata style cleanup