bashate: ignore files

[Matt Taggart]

I have noticed when running bashate on source trees that a few file standard files result in lots of output. For example, in one project I found:

config.guess had 9551
ltmain.sh had 656

This was far larger than the number of reports for the actual project and isn't of interest to the developer.
It would be nice to have a way to exclude certain files, some ideas

* support regexs
* support both specifying with a command-line flag and also loading a file, maybe like tar's
  --exclude=PATTERN
  --exclude-from FILE
* possibly have a standard list of excludes, like those above and maybe .git .svn etc.
* possibly note when a file is encountered and is skipped (maybe configurable)

Thanks