DLTP-213 Reworking on function to write fedora message to custom channel

Adding function to write message to  custom channel

Adding rspec-given
Log exception that occured on attaching files
Spec to test the new config method

Combining DLTP-189  Replace blue warning edit button to orange warning resolve button empty file

This method is confusing to read, compare the following:

```ruby
Curate.configuration.deliver_fedora_integrity_message.call(options)
```

and

```ruby
Curate.deliver_fedora_integrity_message(options)
```

When I send `Curate.configuration` the `deliver_fedora_integrity_message`, I assume that it will do just that. Not return a "callable" object to which I must then send the message `call`.