Improved Logging and fixity manifests

[bb233]

This pull request

• Adds size information to generated fixity manifests.
• Adds contents of fixity diffs to comparison errors.
• Logs Start and completion of processing of all messages

It also improves the testing of logging functionality.

[coveralls]

Pull Request Test Coverage Report for Build 89

• 88 of 94 (93.62%) changed or added relevant lines in 10 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage increased (+0.8%) to 91.091%

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Changes Missing Coverage	Covered Lines	Changed/Added Lines	%
lib/archival_storage_ingest.rb	9	12	75.0%
lib/archival_storage_ingest/s3/s3_manager.rb	1	4	25.0%
<!--	Total:	88	94	93.62%	-->

Totals
Change from base Build 82:	0.8%
Covered Lines:	910
Relevant Lines:	999

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💛 - Coveralls

[sk274]

When logging the status of the work done, I think it would be enough to just record the status and the ingest_id, rather than recording the status and the whole ingest message which we already have at the beginning of the work.

[bb233]

I've made that suggested change. Does it look good now? @sk274