Generalized error and failure system

[michaelpb]

More thoughts on error

• Keep a stdout.txt, stderr.txt, and error.log conversion log for each foreign resource, of all stdout/stderr generated... something like aef/a94a/e4/2b/_logs/stdout.txt

• Make CLI commands that can show browse log for certain files

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• Need to have a generalized failure system that permits retries, conversion failures, etc, and escalation after X retries

• For both ConversionGrid and ResolverGrid

• Possibly handle "invalid" stuff too

(from git resolver)
44 # NOTE: Should do validation on GIT resource urls, notably disallowing
45 # HEAD, and branch names (should only be tags or commit hashes)

110 # TODO: Have failure handling here, if this command fails and can't find
111 # given hash, it should attempt to update, if that fails, then we know tha
112 # the specified "tree object" does not exist, 404