Add support for colors in log output

[dogonthehorizon]

As a Bartlett user, I would like the option to enable colors in log output if the upstream job has enabled them, so that I can easily distinguish events in my builds.

Notes:

• I'm not actually sure if this is currently possible. It may require parsing the HTML endpoint instead of the progressive text endpoint to access these colors.

AC:

• log and build sub-commands support option to display log output with colors