Change request: FNPATTERN matching string

["Francesco Duranti" <fduranti (at) q8.it>]

Hi Henrik, just another little request.
The FNPATTERN is matched as a regular expression and this could is some
situation cause problems matching the right file.
For example I'm creating some rrd named xtradisk,diskname.rrd and they
get matched with the normal disk test and I start to not get any disk
graphs from disk and trend column.
The simple solution is to put a "^" in front of the disk in the
hobbitgraph.cfg. This is good for this test until the next one that will
try to get wrong data.