Minor improvements to Issues UX

[jasonmp85]

I put a lot of time into making the Label icons and colors nice, but threw in the towel after a few colors, and am still not sure about a few of the labels…

• Decide whether the Effort icons are what we want (some form of progressing smileys could be a reasonable alternative)
• Finalize background colors for Needs, Area, and State categories. Use this site to determine good candidates for background colors (use prominent icon colors and see what it suggests)
• Where does testing go as a category? Continuous integration? Tools, Automation, and Docker also seem to have some overlap