Add ppl grep command
Add a simple cucumber test for the new git grep passthru command
Version 2.3.0: ppl grep

With thanks to @ajford for the excellent feature request, version 2.3.0 brings a
new command: ppl grep. This command leverages the
extremely high speed search git grep repository search in order to provide
near-instant search results.

    $ ppl grep smith
    john.vcf:EMAIL:john.smith@example.org