Replace "spermy" with "approximate" to mirror the RubyGems change in terminology
in pull request https://github.com/rubygems/rubygems/pull/124
Fixed grammar.
Changed "approximate" to "optimistic" per the consensus from @orta, @irrationalfab and @Kapin.
Merge pull request #76 from luisdelarosa/approximate_version_operator

Replace usage of the term "spermy" with "optimistic".