Remove Makefile in favour of Grunt

Available tasks

          sass  Compile Sass to CSS *
     modernizr  Build out a lean, mean Modernizr machine. *
        jshint  Validate files with JSHint. *
        concat  Concatenate files. *
        uglify  Minify files with UglifyJS. *
         clean  Clean files and folders. *
         shell  Run shell commands *
         watch  Run predefined tasks whenever watched files change.
         bower  Manage client-side dependencies via Bower
       compile  Compile JS and Sass files
       install  Run Bower and Composer installs
            js  Concat and minify JavaScript
          test  Run `scripts/test`
          lint  Validate files with JSHint
       default  Does nothing
Update Travis CI config (commands, notifications)
Update README file
Fix words/spelling mistakes
Update CONTRIBUTING document
Merge pull request #110 from whymarrh/develop

Grunt build system (with document updates)