Fix bug in filter code that caused Rubinius failures

Although this was fixed in commit bc7c532c5 (by forcing the values to be
Strings if they are Symbols), this commit fixes the underlying problem.

The real bug was in allowing the Symbol :all to remain in the Regexp
list when it is not needed. The :all and :none modes don't use a Regexp
and so @rex is now set to nil in those cases.
Fix bug in filter code that caused Rubinius failures

Although this was fixed in commit bc7c532c5 (by forcing the values to be
Strings if they are Symbols), this commit fixes the underlying problem.

The real bug was in allowing the Symbol :all to remain in the Regexp
list when it is not needed. The :all and :none modes don't use a Regexp
and so @rex is now set to nil in those cases.
Merge remote-tracking branch 'origin/filter_fix_regex_symbol' into filter_fix_regex_symbol
Merge pull request #1191 from townsen/filter_fix_regex_symbol

Fix bug in filter code that caused Rubinius failures
Comment out cucumber feature which is misleading, keep for reference
Fix rspec assertion be_false != be_falsey
Preparing Release v3.3.3
Fix README to make Ruby version explicit
Mention the metrics
Update README.md
Merge pull request #1200 from seuros/patch-1

Update README.md correct version
Update copyright
Fix README
Merge pull request #1201 from seuros/patch-1

Update copyright
Fix v3.3.3 compare links
Merge pull request #1204 from deeeki/fix_compare_links

Fix v3.3.3 compare links in CHANGELOG
fix flag for ls-remote
Update git_spec.rb
Merge pull request #1215 from dimitrid/master

fix flag for ls-remote
Update README.md

Small typo.