Allow more powerful grepping in Base grep method.
Allow more powerful grepping in Base grep method.

Signed-off-by: Scott Chacon <81ce51881e261567723ba832f9c004d3d8116425@gmail.com>
Alwahsh/ruby-git,StudyTube/ruby-git,ai-traders/ruby-git,modulexcite/ruby-git,henrybissonnette/ruby-git,hybridgroup/ruby-git,hybridgroup/ruby-git,onetwotrip/ruby-git,schacon/ruby-git,Alwahsh/ruby-git,ai-traders/ruby-git,henrybissonnette/ruby-git,modulexcite/ruby-git,fastlane/ruby-git,fastlane/ruby-git,StudyTube/ruby-git,onetwotrip/ruby-git,fleitz/ruby-git,lispro06/ruby,fleitz/ruby-git,schacon/ruby-git