Implement the Ceres storage backend against TimeSeriesDatabase

[iain-buclaw-sociomantic]

With the other TimeSeriesDatabase changes now in. Adding ceres (or any other backend) support into carbon is relatively straightforward.

This patch implements Ceres support.

[obfuscurity]

LGTM

[iain-buclaw-sociomantic]

I should also say that what's missing are ceres maintenance files, some of which are found in the megacarbon branch here:

https://github.com/graphite-project/carbon/tree/megacarbon/plugins/maintenance

[obfuscurity]

@iain-buclaw-sociomantic Planning a separate PR for those?

[iain-buclaw-sociomantic]

Can do if you think it's best to have it in carbon, maybe under some third party directory? I don't know how integrated you'd like ceres to be. :-)

In any case, after the maintenance files, I guess that's the megacarbon branch finished.

[obfuscurity]

Nah, I'd assume we want that to remain in the Ceres project, but in master.

[iain-buclaw-sociomantic]

OK, so I'll check that there are no dependencies on carbon (these are standalone maintenance plugins) and raise the patch against graphite-project/ceres.

[iain-buclaw-sociomantic]

Thanks.