Switching screens in the PIM Prototyping

[nathanielw]

Narrative:
As a user
I want a way to choose which screen to edit
So that I can edit multiple screens of the prototype

Acceptance Criteria:

Scenario 1: Providing the required menus
Given At least two images have been loaded into the builder
Then a dropdown menu exists that lists these images

Scenario 2: Selecting the screen
Given At least two images have been loaded into the builder
When an item is selected from the dropdown
Then the screen being edited is swapped for the one that was selected from the dropdown
And the state that the previous screen was in is not lost