and also -f should override detection

fixes #343

instead of aborting

Tab format needs to use absolute paths to work properly with Jenkins.
HTML format does its own thing but always displays relative paths in
expanded warnings. Text and CSV reports do not include file names.

which is not the default for the command line,
causing all sorts of annoyance.

needs better name?

Conflicts:
	lib/ruby_parser/bm_sexp.rb

* Cleans up duplicated logic for skipping files
* This is not being used for the install_rake_task behavior

closes #164

User could compare with the **baseline** json file ignore base directory.

instead of returning false for options[:exit_on_warn]

instead of when reporting, which lead to confusion
and filtering all over the place instead of in one place.

although we're still depending on "globals",
just not ones shared with every Ruby app