Allow escaped and unescaped single and double quotes in metric names.

[wnpayne]

This change would allow single and double quotes both escaped and unescaped in metric targets, with the goal of more closely matching the behavior of graphite-web, which allows both.

Not attached to the formulation of the below, just interested in the end results. I am using (and loving) graphite-api as a (much simpler!) graphite-web and this is the first notable discrepancy reported by our users.

[brutasse]

Thanks for this -- looking at the same code in graphite-web, I don't see why graphite-api's behavior would be different than graphite-web's:

• https://github.com/graphite-project/graphite-web/blob/master/webapp/graphite/render/grammar.py#L57
• https://github.com/graphite-project/graphite-web/blob/master/webapp/graphite/render/grammar.py#L79-L80

These seem to match what we have in graphite-api. Or did I miss something?