Updating constructor variables to be directly on the model
Updated menu selection logic
Updated menu save function
Added classes for type and refactored adding classes
Merge branch 'develop' into menu-editing

* develop:
  misc - fixed missing event param in editorMenuLayerView.js
  Removed t2() handlebars helper
  Removed call to fs.existsSync
  Removed call to localstorage.setItem()
  Implementation of multi-lang support
  Translation replacements
  Adding placeholder support for localisation - Handlebars lib v1.3 added - Handlebars dev dependency updated
  Addition of Polyglot.js for multi-lang support
  Re-work to allow persiting of the navigation
  Minor re-work to router
Merge branch 'menu-editing' into develop

* menu-editing:
  Added classes for type and refactored adding classes
  Updated menu save function
  Updated menu selection logic
  Updating constructor variables to be directly on the model

Conflicts:
	frontend/src/core/editor/models/editorArticleModel.js
	frontend/src/core/editor/views/editorPageEditView.js
	frontend/src/core/editor/views/editorView.js
	lib/contentSchema/Course.schema
Fixed merge issues # with '#' will be ignored, and an empty message aborts the commit.
Merge branch 'develop' of https://github.com/adaptlearning/adapt_authoring into develop

* 'develop' of https://github.com/adaptlearning/adapt_authoring:
  Fixes for content plugin
  Adding course config edit feature

Conflicts:
	frontend/src/core/editor/models/editorCourseModel.js