Fixed a regression introduced by commit #54c57330c419a597078170143398b33427114ae0

Conflicts:
	app/models/forem/topic.rb
Added a regression test on the topic nodel
Add sass-rails and coffee-rails dependencies

Necessary for new forem layout added recently
Include forem_atom_auto_discovery_link_tag in the default layout
Use class for flash tag in default application layout
Add asset generation step mention to install generator
Bump database_cleaner and devise versions