Feature: Add guard watch and guard logger.

[JosephCatrambone]

New Features:

• A multiprocessing + async safe logger.
• A watcher command that can read (and tail in realtime) the logs.

TBD:

• Where do we want the default location of the log file to be? (Defaulting to temp directory.)
• What do we want the maximum lifetime of a log to be? (Defaulting to 100000 entries.)
• What is the performance impact of the additional logging?

Performance implications:

• Without logging: 7.99 seconds, 7.99 seconds, 8.04 seconds, 7.83 seconds, 7.97 seconds (Mean: 7.96sec +- 0.70sec)
• With logging: 7.97 seconds, 7.82 seconds, 7.99 seconds, 7.81 seconds, 7.93 seconds (Mean: 7.90sec +- 0.75sec)

[CalebCourier]

LGTM! Last comment: Have we tested this with the guards running server-side as well as client-side? It's just interacting with a file so it looks like it should work in both scenarios, but we should be sure to test both.