Improve resources configuration

[tarekziade]

The configuration for kinto.signer.resources is hard to read and makes it super easy to make typos (we did) - and nothing prevents the signer to catch them

what about this

kinto.signer.resource.one = staging/foo , target/foo 
kinto.signer.resource.two = staging/baz , target/baz 
kinto.signer.resource.three = staging/boh , target/boh 

with one extra verification: if the split(',') can't produce 2 elements that are URL sub paths we raise a blocker error

[leplatrem]

Related #69

[Natim]

How is this different from:

kinto.signer.resources =
        staging/foo ; target/foo 
        staging/baz ; target/baz 
        staging/boh ; target/boh 

[phrawzty]

Please be aware that in the svcops environment, the templates that build the ini files are populated from a basic key / value lookup. As a result, multi-line values require interpolation, and that makes me nervous. If there's a sane way to stick with a simple, single-line var = value syntax, that'd be preferable.

Fwiw, kinto.signer.resource.<one|two|...> = <value> is a reasonable compromise.

[tarekziade]

In any case, let's verify that we do have tuples of 2 PATHs elements or raise an error

[leplatrem]

we could use => instead of ; to show the worklfow

c.f. #127 (comment)

[leplatrem]

There would be a need also to specify editors/reviewers group by resource