Msftidy: use binary on File.open always

msftidy is complaining, here:

keylog_recorder.rb:116 - [WARNING] File.open without binary mode

Not sure how this managed to hit upstream/master with msftidy warnings.
Protip, use an msftidy pre-commit hook. We have just such a hook script
in tools/dev, as a matter of fact, so it's just a symlink away:

https://github.com/rapid7/metasploit-framework/blob/master/tools/dev/pre-commit-hook.rb
Fix require
Land #2322, @todb-r7's fix to make File.open msftidy compliant
Merge pull request #2323 from jvazquez-r7/fix_python_load

Fix require on Python bind_tcp stager
Retab should optionally keep local backups

Local backups are generally not needed since you can just git checkout
old versions anyway before committing. It was nice to have during dev
but generally shouldn't be done now.
Land #2324, make retab backups optional