[style] Add missing blueGrey colors

[peteratticusberg]

the blueGrey color is missing the colors A100, A200, A400, and A700 as well as the contrastDefaultColor setting which causes Material UI to throw an error if it was chosen as the primary or accent color.

This adds those in :)

[oliviertassinari]

Where have you found those colors? I can't find them in the spec https://material.io/guidelines/style/color.html#color-color-palette. Also, we would need to update the docs if we move forward.

[peteratticusberg]

Ah, good points on both counts.

Brown is also missing colors A100, A200, etc. in the spec and the way we dealt with that was by just setting A100 to the same color as 100, A200 to the same color as 200, etc. I saw that and just did the same thing for blue grey ¯_(ツ)_/¯.

export const brown = {
  50: '#efebe9',
  100: '#d7ccc8',
  200: '#bcaaa4',
  300: '#a1887f',
  400: '#8d6e63',
  500: '#795548',
  600: '#6d4c41',
  700: '#5d4037',
  800: '#4e342e',
  900: '#3e2723',
  A100: '#d7ccc8',
  A200: '#bcaaa4',
  A400: '#8d6e63',
  A700: '#5d4037',
  contrastDefaultColor: 'brown',
};

I propose we do one of the following:

1. Remove Blue Grey, Brown and Grey from colors.js. None of them have defined A* values in the material-ui spec, we don't want to invent A* colors, and colors without A* values break themes.

2. Invent our own temporary A* values for Brown, Blue Grey, and Grey for the time being that approximate what those values might be. After looking at the spec, the mapping I did here is not accurate. An improved version would look something like A100 -> 200, A200 -> 400, A400 -> 600, and A700 -> 800.

What do we think?

I feel like (1) is probably the right thing to do though I'm using Blue Grey for a project of mine so I'm tempted to do (2).

[oliviertassinari]

I'm gonna approve that PR for consistency with the other colors.
I would rather keep those colors and make apply an interpolation function util we the specification is explicit. What do you think?

[peteratticusberg]

I think this is fine for now :)

If we were going to go as far to make a special function for computing the A* variants of a color, I'd think it'd also be worth creating methods to generate the shades 50-700 based off a single color as that would enable users to specify a single color for which we could auto-generate a whole palette.