Make utility functions available globally.

+ Extract functions into separate module.
Move translation helper into Util module.

+ Add basic specs.
Refactor translation helper to return English word if German term is missing.

+ Fix typo in `translateString()` in if-clause.
Merge branch 'feature/refactor-utils' into prototype
Fix error text parsing when "errors" is of type "string".
Reduce amount of scoped variables.
Change rescue order so that CanCan::AccessDenied is handled.
Rename JSON response key "errors" to "error".
Extract response failures into helper.

+ Add I18n exception message for CanCan::AccessDenied error.
Replace response failure with helper method.
Rename JSON response key "errors" to "error".
Add translations for MessagesController responses.

+ Replace "error" with "message" in JSON response for success.
Replace "message not sent" failure expectation with helper method.
Replace "invalid recipient" failure expectation with helper method.
Merge branch 'feature/rspec-response-helper' into prototype
Update the success signature to include the default parameters.
Enable error message for unauthorized edits.
Merge branch 'feature/show-error-message-for-unauthorized-edit-75' into prototype