Preserve executor HealthCheckerThread name

Testing Done:

$ ./build-support/python/isort-run
$ ./build-support/python/checkstyle-check
$ ./pants ./src/test/python/apache/aurora/executor:all

Bugs closed: AURORA-682

Reviewed at https://reviews.apache.org/r/25337/
Add a factory to produce OneWayUpdate instances based on job state and update settings.

Bugs closed: AURORA-613

Reviewed at https://reviews.apache.org/r/25356/
Serve HTTP assets out of a standard classpath root.
Two problems remaining - /apibeta leaks true path location, running from intellij is not working.