Added a ping/pong API
Allow ping & pong to include data, and add docs
Add API for sending unsolicited pongs
Added simple example of using ping & pong
Added a simple test for sending pings & receiving pongs
Merge branch 'ping_pong'
Removed some uneccessary timers from the specs
Moved helper which is only used in one spec
Released version 0.3.6
Force MaskedString#getbytes using encoding ASCII-8BIT, or else it will use the default encoding which may cause problem
Merge pull request #72 from sishen/master

MaskedString#getbytes may return the utf8 encoded string
Refactor error code classes and support 1009 code

* Renamed DataError to WSProtocolError to be consistent with the specification terminology, and made it clear that this always represents a closing scenario
* Added comments to other errors to clarify their use
* Added WSMessageTooBigError with associated 1009 error code
Move maximum frame length to connection object
Add frame length check to Framing07

It should have been there all along
Allow max_frame_size to be configured

Can be configured globally and per connection
Merge branch 'configurable_size_limit'
Raise HandshakeError on malformed requests (empty header)
Added spec for empty header bug
Merge branch 'error-on-empty-header'
Optimise lookup of encoding when sending frames