Tweak metric naming for file_* and *_now values
Tweak metric naming for file_* and *_now values

Addresses issue #72 by removing plurality, moving from file to inode for naming purposes, and removing all cases of appending _now to metrics to denote instantaneous values.

Signed-Off-By: Joe Handzik <91435a5354fd1941fa818cc717e722f572f40c0d@hpe.com>

HewlettPackard/lustre_exporter