Multiple fixes

* Fixed secret_token being set by default. Instead, raise an error and instruct the user in how to generate their own token.
* Fixed multibyte string slicing bug in messages table view (for 1.9 only - is 1.8 supported?)
* Added test and development environments to the example configuration files to make it easier for developers.
* Minor: Updated Kaminari version to eliminate deprecated `ActiveSupport::Concern` usage, which was spamming up the logs with deprecation notices.