Update the 1x shields' colors for review

This changes the green, yellow, red and gray badges to match each other,
using the Travis badges' colors as reference. The 1.0 and 3.0 Code
Climate badge colors were determined using the midpoints between 0.0,
2.0 and 4.0.

Consistency is key!
Merge pull request #20 from laserlemon/master

Make badge colors more consistent