Configure Watch task in Gruntfile

Add config for and load the Watch task (intended to later automatically preprocess the source code for development previewing) in Gruntfile.js;
set it as default task for Grunt in Gruntfile.js.
Add Grunt badge to README

Add Built with Grunt badge to README.md.
Configure JSHint task in Gruntfile

Add config for and load the JSHint task in Gruntfile.js;
set it as task for the watch task (to be executed on a file change) in Gruntfile.js.
Fix JSLint and whitespace complaints in Gruntfile

Add semicolon after last } in Gruntfile.js;
add new-line at eof of Gruntfile.js.
Tweak description in package.json

Add dot at the end in the description field in package.json.
Merge branch 'feature/grunt'