Only give extra debugging output if -v given

Some extra debugging in the github version of this code outputs extra text.

eg.
checking warning
range was warning
(0, 1.0, False)
0.253954543692:0:1.0 =  False
checking critical
range was critical
(0, 2.0, False)
0.253954543692:0:2.0 =  False

This all comes out BEFORE the status line and makes it a little more difficult to track in Nagios. 

I've made a patch that checks if verbose (-v) was specified on the command line, and only display those extra lines when true.

Cheers,

Joel