Rails 4: Removed reference to nonexistent Actions module.

See gregbell#2120 by @akashkamboj.
Rails 4: A Name is not a String, so use Name methods.

Or convert the Name to a String.
Don't add Devise config twice.

This substition was being made twice by the `install` generator,
resulting in two config parameters. Now we only add the config
if there is none already.