fixes #2481 - invalid state in BMC power dropdown
fixes #2490 - filter empty EC2 security groups
fixes #2492 Fallback to assets pipeline if a precompiled asset is missed in production

That's the case when an engine (foreman plugin) with it's own assets is added to
Foreman later in production.

this patch ensures that while not precomplied, it does not fail in
production.
English edits in prep of Capybara testing
Fixes #2272 - added Capybara integration tests