fixes https://github.com/TryGhost/Team/issues/3331
This adds attribution tracking to the signup form. It sends a newly
created url history when sending the signup API call, this url history
will get translated to a proper attribution and saved on the backend. We
send a history with only a single item that contains the referrer
source, medium and path of the Embed form.
This also makes some changes to the E2E tests so that the tests run
in an https environment instead of about:blank.
As discussed with the product team we want to enforce kebab-case file names for
all files, with the exception of files which export a single class, in which
case they should be PascalCase and reflect the class which they export.
This will help find classes faster, and should push better naming for them too.
Some files and packages have been excluded from this linting, specifically when
a library or framework depends on the naming of a file for the functionality
e.g. Ember, knex-migrator, adapter-manager
