Add a utility binary that compresses and encrypts backup files per the spec.
Use the encryptor binary to encrypt the unencrypted test case file and include
it as an additional golden test. Check that, in addition to calling via the
library, the binary also accepts valid test files.
Adjust the attributes so that git will treat the generated acknowledgment files
as binary for the purposes of merging. This will ensure that a merge of two
branches that both alter the acknowledgments will require manual resolution
(ideally by re-running the generation script).
