Move method_cache_busters script to script directory.
Add missing grep -v filter.
Add a line to ignores to always keep.
Fix script so that blank lines are fine in the ignores file.
Label option parser as not part of RSpec's public API.
No need for `parse` and `parse!` aliases.
Remove unneeded `abort` alias.
Add a bunch of ignores.
Merge pull request #1173 from rspec/remove-cache-busters

Remove cache busters