Make gruel able to change the output file name

[jwir3]

It's non-trivial in android builds to change the file name of the output to contain something like the git commit hash. However, since this is a solved problem, we can incorporate this into gruel so that we can add the following to our build.gradle file:
t

buildTypes {
  debug {
    outputFileNameSeparator = "-"
    outputFileNameComponents =[ "%projectName%", "%versionName%", "%gitCommitShaShort%", "%alignmentSigningStatus%"]
    outputFileNameAppendBuildType = true
  }
  release {
    outputFileNameSeparator = "-"
    outputFileNameComponents =[ "%projectName%", "%versionName%"]
    outputFileNameAppendBuildType = false
  }
}

The following variables will have to be populated by gruel:

• projectName: The name of the current Project.
• versionName: The versionName field of the current build.
• gitCommitShaShort: A shortened version of the git commit sha (we might also need a long version).
• alignmentSigningStatus: Whether this is signed, unaligned, etc... (probably only useful for android builds).