Merge pull request #9 from hgrohne-cygnusnetworks-de/newifacekeyerror

fix a KeyError
Merge pull request #8 from hgrohne-cygnusnetworks-de/excludere

added -X --excludere flag
New optional argument to specify an alternate data file: fixes #10. (plus default values are all in the main() function
bump version 2.6, specify the bandwidth type in the argument parser (instead of using int()  ). Don't why I didn't do it before...
Merge remote branch 'samyboy/master'

Conflicts:
	check_iftraffic_nrpe.py (Severe conflicts. Diverged handling of
        bandwidth. Different options and so on.)