Setting directoryUrl doesn't work properly #57

Setting directoryUrl needs to be done on the manager, but the manager wrapper doesn't have directoryUrl as an allowed option - so Greenlock warns when it is set.

To make this more frustrating, Greenlock takes directoryUrl as configuration option and seems to use it in the code (in gconf) - but never actually uses it.

The dead code referencing directoryUrl from gconf should be removed, and directoryUrl should be added as a known property for manager options.

Agreed.