Improved uniqueness of defaultClient

relates to issue #26
Fixed a globally leaked buf in generate.js
Moved all tests to using mocha.

* Added devDependencies
* Generate mocha tests dynamically from old json cases
Removed old tests
Added some more tests.

Mainly for lib/connection and lib/mqtt
Fix for callback as single argument to mqtt.createClient

The callback was overwritten with defaultPort.
Changed the order of assignments to make it work.
Added tests for QOS.

Inspired by comments in issue #18
Added tests for TLS Client.

Only does a simple connect
Included self signed certs.
Smarter port assignment so it minimize the risk of EADDRINUSE
Merge pull request #29 from kmpm/multiclient

Improved uniqueness of defaultClient
Merge pull request #30 from kmpm/leaks

Fixed a globally leaked buf in generate.js
Merge pull request #31 from kmpm/mocha

Moved all tests to using mocha.
Merge pull request #32 from kmpm/fixes

Fix for callback as single argument to mqtt.createClient
Changed npm package name (to mqtt) and bumped version number
Updated README.md to reflect package name change
Update require paths in examples