Refactor conditional to pass required setting tests.
Refactor conditional to pass required setting tests.

If a setting is defined in a subclass and is not None do not raise
config error.

facetoe/i3pystatus,yang-ling/i3pystatus,enkore/i3pystatus,enkore/i3pystatus,ncoop/i3pystatus,teto/i3pystatus,teto/i3pystatus,facetoe/i3pystatus,ncoop/i3pystatus,schroeji/i3pystatus,m45t3r/i3pystatus,richese/i3pystatus,yang-ling/i3pystatus,drwahl/i3pystatus,Arvedui/i3pystatus,Arvedui/i3pystatus,fmarchenko/i3pystatus,fmarchenko/i3pystatus,schroeji/i3pystatus,drwahl/i3pystatus,richese/i3pystatus,m45t3r/i3pystatus