Parser updates

* MultiSite now has backend aware helper functions
  * get_contact()
  * get_host()
  * etc ...

* Config.guess_binary() was improved
  * Uses "which" command instead of a built in list
  * Recognises nagios, naemon, icinga, shinken
New Modele: pynag.Utils.misc

* Contains the class FakeNagiosEnvironment
  * Will be useful for more isolated testing
Utils.misc - code cleanup and improve doctests