updated readme, cleaned up some deprecated methods
Merge remote-tracking branch 'aschuch/documentation' into update-readme

Conflicts:
	README.md
Various README improvements:
* Use correct syntax highlighting
* Added notes on channel lifecycle
* Added notes on memory management with block-based event listeners
Revised notes on handling disconnections.
This is not relevant
Link directly to error code documentation
libPUsher, not PUsher
Merge pull request #126 from lukeredpath/update-readme

Update README for 1.5