Remove generated email_processor route

* Not everyone will want to use the same `/email_processor` path
  for their incoming emails
* Rails no longer [plays nicely] with named routes.
  https://github.com/rails/rails/commit/a2b7c0e69d671294067b625c749be6fdbec7b433
Update to RSpec 3.0

* Fix deprecations (rspec/autorun, should syntax)
* Fix failures (type: :controller)
Use table for README.md definitions
Remove Mandrill adapter and use griddler-mandrill