Organize issues with Labels (and maybe milestones)

[kalimar]

Make it easier to get involved by adding labels and perhaps milestones for the site.
Here's an example https://robinpowered.com/blog/best-practice-system-for-organizing-and-tagging-github-issues/

[craig-riecke]

This is a good labelling system, but are we applying it to just this repo or across the board? Definitely some labels will become standards like Help Wanted (to implement #122).