Remove use of Numeric#positive? and Numeric#negative? (#105)
Remove use of Numeric#positive? and Numeric#negative? (#105)

These two methods on `Numeric` were added in ruby `2.3` and we're
currently using this gem in services that run on ruby `2.2.0`.

Related ruby core feature request: https://bugs.ruby-lang.org/issues/11151
codeclimate/codeclimate-services,codeclimate/codeclimate-services