Add controller, routes and HTML/JS views for newsletter subscription
[WIP] Newsletter sign up
Add newsletter subscription entity.
Add newsletter subscription decorator.
Add newsletter subscriptions repository.
Add newsletter subscriber as an interactor.
Add newsletter subscriptions controller and route.
Use rails helpers to render localised newsletter subscription form.
Style newsletter subscription form.
Add border separator

I will match the height of this once we alter the content in the other
columns within this row
Add authenticity token to newsletter sign up form.
Define connection post method to handle HTTP 422 status response.
Display localised success and error messages on signup subscription.
Add newsletter signup feature, steps and page object.
Update bubble with new design
Update newsletter design
Update variable name from colour to color inline with others
Update Contact sections as per design
Update contact bar layout
Alter copy on hidden email <label> on newsletter signup