Added options object that allows the user turn off the output file hash,...

... and also include a version string in the filename.

Tests pass.

  ✓ should rev files
  ✓ should not rev files if hash is false
  ✓ should rev and version if version set
  ✓ should not rev but add version if version set and hash is false
  ✓ should build a rev manifest file
  ✓ should allow naming the manifest file
  ✓ should append to an existing rev manifest file
  ✓ should respect directories
  ✓ should store the hashes for later

  9 passing (17ms)
In your own usage of this plugin, have you decided to rev in every build environment? How about uglification? https://github.com/sindresorhus/gulp-ruby-sass#style for instance, has options that I would use in dev and not production, like style:expanded. I view these rev options the same way, to help in different ways depending on the environment the code runs in.