add `dist` target to make

add uglify-js module (need npm install)
add rules for building .gz and .min.js files to Makefile

running `make dist` will build
  furkot-plan-microdata.min.js
  furkot-plan-microdata.min.js.gz

--wrap $(PROJECT) option passed to uglify embeds entire script in a
self-executing function ensuring we are not adding anything to global
namespace - that's important for script that is to be included in a 3rd
party pages
Merge branch 'dist-targets'