Use more intuitive colours for the cycleability layer

[jf1]

The cycleability ratings layer has great potential to enable better comprehension of and contributions to OSM data, and I feel it would benefit from a more intuitive set of buckets and colours. I think campaigners would also benefit from a unified or at least aligned set of colour schemes across the various sites / tools, so suggest / request that you consider a Red-Yellow-Blue scale with 'Blue is best, red is worst'.

This could be:

More info in this related issue: cyipt/cyipt-website#23

nb. This layer also needs a key, as per: #17