Publish minified files to pdfjs-dist npm package #5487

-Completed feature https://github.com/mozilla/pdf.js/issues/5487
-When "node make dist" command is run JavaScript and CSS files present under build/dist will be minified  and added to same folder.
-Minified files will be named  <file_name>.min.js or <file_name>.min.css
-For minifying css files YUI compressor is needed
-Review required