Build: Break down logic of grunt config

* Use separate jshint config for Gruntfile.js
* Move grunt tasks to separate modules
Build: Use exact versions dependencies
Build: Add scripts property to package.json
Build: Install qunit lib through grunt task
Build: Download speed dependencies through grunt
Doc: Reflect build changes in the README file
Build: Check code style issues through jscs
Build: Add ".editorconfig" file
Build: Add grunt test task and npm build script
Build: Update uglify options
Build: Unite all lint commands

And mention "grunt -help" command in readme