cleaning up the colors. Fixes #468

Fixes #468

> All #f3f5f6 and #eaeaea to #f2f2f2
> All #f00 to #d63920
> All #414e58 and #454f59 to #424f59
> All #0092db and #0096dd to #0095dd
> I believe #0088cc is correct for hover and active on the big button

New color list from /app/styles/main.css is:
```
I found 8 unique colors in ./fxa-content-server/app/styles/main.css
#0088cc: 1
#0095dd: 6
#424f59: 8
#5fad47: 1
#8a9ba8: 14
#d63920: 2
#f2f2f2: 6
#fff: 8
```