Adds record.Marshal and record.Unmarshal.
Uses record.Marshal() and Unmarshal() in tests.
Remove templating system + generalize log interface tests.

Use sink chaining instead of explicit templating.
Adds a generic SinkFunc for creating more kinds of sinks.
Implement InfoSink so we can factor out info writing from logger.
Remove Logger type as we don't really need them.
Extract levels into its own type and file.
Adds tdd target with screen clearing when repeatedly ran
RecordBuilder fully working as a Log implementation.
Adds a NilSink for non-output testing.
Entrypoint constructor for bunyan.