Add link to external testing guide
Merge branch 'master' of github.com:mgechev/angularjs-style-guide

* 'master' of github.com:mgechev/angularjs-style-guide: (25 commits)
  improves pt-br translation correcting some things
  Add a Bitdeli badge to README
  style fixes + harmonize code examples
  translate section about services
  translate section about filters
  translate section about directives
  translate section about controllers
  translates section about templates
  translates section about routing
  translates section about contributions
  cleanup
  sync
  fix typos
  synchronize de with en
  Fix pluralization, grammar, and typos.
  Update README.md
  Update README-pt-br.md
  synchronizes de with en
  translates chapter "modules"
  translates chapter "others"
  ...