Network module responds poorly to ifcfg-NNN.bak files
(network-#36) Better validation around ifcfg script names

This extracts the filename regex to a class constant. It also adds an
optional parameter for `self.target_files` for the purpose of testing. It
also switches from `Dir.glob` to `Dir.entries` to use full regular
expressions instead of the limited dir globbing expressions.
Merge branch 'pull-37'

This closes GH-37 and GH-37
Add .gitignore for all spec fixture modules
Merge branch 'maint-gitignore_spec_fixtures'