change build system to gulp: add gulpfile.js, add package.json, ignore node_modules, update README.md
Merge branch 'master' into feature--gulp-file

* master:
  Update hide-text extend
  update contributing.md with semantic versioning and git branch model, fixes #3 and fixes #43
  feature--html-snippets: add generic toggle script, add icon pattern, add toggle icon, add is-hidden helper class
  higlighttable: make font-size smaller
  add html snippets, add syntax highlighting styles, add line numbers, fix spacing on media patter, tweak the styleguide grid
gulpfile: add sourcemap
gulpfile: add js concatenation, change js to modules
Merge branch 'feature--gulp-file' into develop

* feature--gulp-file:
  gulpfile: add js concatenation, change js to modules
  gulpfile: add sourcemap
  change build system to gulp: add gulpfile.js, add package.json, ignore node_modules, update README.md