Fix a command line flag issue

This should fix https://github.com/namecoin/nmcontrol/issues/26 .  Can everyone please test this for regressions relating to command line option processing?  I don't expect it to cause problems, but it definitely changes the data that services are receiving.

In particular, the most likely command line option to be adversely affected is --dns.disable_ns_lookups=0 and/or --dns.disable_ns_lookups=1 .  That option seems to work fine for me.  But additional testing would be appreciated.