Colorful output

[seaneagan]

Specifically:

• distinguish output from grinder itself from task output
• display errors in red, warnings in yellow.
  • Should be supported in unscripted soonish: Log formatter which uses different ansicolor depending on log level seaneagan/unscripted#3
• nicer help output
  • unscripted has semantically highlighted (and automated) help output.

[devoncarew]

We have it, but do have issues with not always being able to detect an interactive terminal.