Fix exception thrown when running blessc --help

[mtscout6]

The help cli tools is currently throwing an error.

➜  bless git:(master) ./bin/blessc --help
BlessCSS v4.0.0-alpha.1 - Tools to ensure CSS files meet IE 6-9 selector limit restrictions.

Commands:
  count  checks an existing css file and fails if the selector count exceeds IE limits
  chunk  breaks up css file to multiple files if it exceeds IE selector limits

Options:
  --version, -v  Show version number  [boolean]

Examples:
  bin/blessc count <file|directory>
  bin/blessc count <file|directory> --no-color
  bin/blessc chunk <input file|directory>   (chunked files will reside next to input css files with the format *.##.css)
  bin/blessc chunk <input file|directory> --out-dir <output directory>
  bin/blessc chunk <input file|directory> --sourcemaps

For additional information see http://blesscss.com

/Users/smithm/dev/bless/bin/blessc:8
  .then(function(exitCode) {
   ^
TypeError: entry(...).then is not a function
    at Object.<anonymous> (/Users/smithm/dev/bless/bin/blessc:8:4)
    at Module._compile (module.js:426:26)
    at Object.Module._extensions..js (module.js:444:10)
    at Module.load (module.js:351:32)
    at Function.Module._load (module.js:306:12)
    at Function.Module.runMain (module.js:467:10)
    at startup (node.js:117:18)
    at node.js:946:3