codeception/verify 2.1 removed support for expect()->stringContainsString() so we need
to replace it with verify()->stringContainsString().
[MAILPOET-5664]
I envision the StylesController as the source of information about
styles settings in both the editor and renderer.
We will add email styles settings and these will be accessed in PHP via this service.
[MAILPOET-5540]
