Response Messaging Message File New Line Fix

The response messaging service is able to construct a response body by using the contents of a file as a template. Unfortunately, we were reading the file line by line, and we were not replacing the newline character as we did so, so new lines were removed in the response.

To solve this issue, I've brought in the Apache commons IO library to handle reading the file and removed our custom file reading code.

NOTE: If/when this PR gets merged, the release notes should be updated.
It is. The dependency management is in the repose-aggregator pom (profile-support) and existed prior to any of my changes. It sets the version to 2.4, which is the most recent.