Add docker-compose configuration for local development

[stephen-soltesz]

This change adds minimal local development instructions and configuration, as well as fixes several bugs in the traceroute-caller code.

The README.md, docker-compose.yaml and "incomplete" databases in ./testdata/* provide the ability to run tcpinfo, uuid-annotator and the traceroute-caller as they would run on an M-Lab node, sharing a single IP address.

This change fixes several bugs:

• Dockerfile now pins the version of ubuntu to a specific version, to prevent changes across builds.
• The default directory mode for data directory is now 0777, to prevent directories without 'write' bits set.
• Sets the TestTime field, which was always empty.
• Removes the static override of the socket filename flag for the uuid-annotator event socket.

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This change is 

[coveralls]

Pull Request Test Coverage Report for Build 59

• 7 of 7 (100.0%) changed or added relevant lines in 3 files are covered.
• No unchanged relevant lines lost coverage.
• Overall coverage decreased (-0.002%) to 97.626%

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Totals
Change from base Build 455:	-0.002%
Covered Lines:	1069
Relevant Lines:	1095

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💛 - Coveralls

[SaiedKazemi]

@stephen-soltesz thanks A LOT for doing this. Being able to test locally greatly improves the development process.