created common module to load shared dependancies
refactor of JS file structure

common module created and modules
refactored to use this common set
refactor analytics

moved basic analytics call into common
changed "analytics" module to be scrollTracking module
as most projects would never need this specific functionality
renamed locale string to pass js validation rules
updated tests inline with JS changes
cleanup require loading
Merge branch 'improvement/js-optimisation' of https://github.com/moneyadviceservice/frontend into improvement/js-optimisation

Conflicts:
	app/assets/javascripts/application.js.erb
	app/assets/javascripts/modules/mas_scrollTracking.js
font caching with localStorage added