Also:
- Added svg loading support (dummy stub) for jest.
- Updated headless test case due to node changes.
- Split out editor change detected to where appropriate.
- Added functions to help with testing, like mocking our context.
Imported at 0.17.1, Modified to work in-app.
Added & configured test dependancies.
Tests need to be altered to avoid using non-included deps including
react dependancies.
