Swapped menu to a template file

* added templates to  "web_accessible_resources" in manifest.json
* getting template via jQuery.get()
Added Lo-Dash for templating

* added Lo-Dash to manifest.json
* changed image url to be rendered by template engin
* template is rendere when loaded via jQuery.get()
Added Lo-Dash to download instructions in readme
Merge branch 'feature/contentScriptTemplating' into develop