Move chalk from devDependencies to regular dependencies

Fixes:

    % ember g proto-scss
    version: 0.1.2
    Cannot find module 'chalk'
    Error: Cannot find module 'chalk'
        at Function.Module._resolveFilename (module.js:338:15)
        at Function.Module._load (module.js:280:25)
        at Module.require (module.js:364:17)
        at require (module.js:380:17)
        at Object.<anonymous> (/Users/zach/code/reddit/node_modules/ember-cli-proto-css/blueprints/proto-scss/index.js:3:13)
        at Module._compile (module.js:456:26)
        at Object.Module._extensions..js (module.js:474:10)
        at Module.load (module.js:356:32)
        at Function.Module._load (module.js:312:12)
        at Module.require (module.js:364:17)