Added option to specify flash policy server address/port and forceFlash,...

Don't be hasty.. this is still open for discussion.

* Gives user the option to specify flash socket policy address/port  and forceFlash (good for testing)
* Adds test case for FlashSockets

Related:
Engine.io pull request - https://github.com/LearnBoost/engine.io/pull/226
Engine.io-client issue - https://github.com/LearnBoost/engine.io-client/issues/232