Changed the rendering of the priority column color based on the priorityColor property

Summary:
I changed the rendering of the bar color for the priority column when running arc tasks to match the priorityColor property.

If the priorityColor property is one of the basic colors already supported by ansi, then the bar is set to that color, otherwise it is set to white.

This will allow the user to customize maniphest priorities and then set their own colors and have those colors display correctly when running arc tasks

Fixed some linting errors

Test Plan:
Run arc tasks and ensure that:

• the priority column is displayed with a colored bar
• the priority column bar is the correct color (or white if it is an unsupported color)

Reviewers: Blessed Reviewers, epriestley

Reviewed By: Blessed Reviewers, epriestley

Subscribers: epriestley, Korvin

Differential Revision: https://secure.phabricator.com/D8735