Added support for multiple users as arguments for owner, op, halfop, voice, and quiet.

One can also prefix nicks with - for negative, or + for positive.
op #Test Foo -Bar
will op Foo, and deop Bar
deop #Test Foo +Bar
will deop Foo and op Bar
Merge pull request #118 from ShutterQuick/atheme+listnicks

Added support for multiple users as arguments for owner, op, halfop, voi...