implement AND of settings

[lpw]

After a few requests for this missing conditional expression, and witnessing the unfortunate workarounds from not having it (usually dropping back to code), this is a overloaded implementation of setting which now also takes an array where each item is a setting and the resulting evaluation is true iff each and every setting also evaluates to true. Similar to buckets or environment taking an array.

- setting: andOfFooAndBar
  value: false
  except:
    - value: true
      setting:
        - foo
        - bar

or

- setting: andOfFooAndBar
  value: false
  except:
    - value: true
      setting: [foo, bar]

This overloads setting in a backwards compatible way by checking the type of setting.

@scsper @juandopazo @cyrils @markandey

I confirm that this contribution is made under the terms of the license found in the root directory of this repository's source tree and that I have the authority necessary to make this contribution on behalf of its copyright owner.

[coveralls]

Coverage increased (+0.02%) to 97.325% when pulling 13932b2 on lpw:settings into 8f356b9 on yahoo:master.

[cyrils]

👍

[scsper]

could we either:

change setting to accept a string or an array (backwards compatible) or deprecate setting in favor of settings (major version change)? i don't like having both setting and settings, as that can be confusing to people

[lpw]

@scsper done

I'd wanted to overload setting but figured there'd be objections to not having tighter typing for validation (didn't want to introduce any major version change, so just overloaded setting).

[markandey]

@juandopazo can you merge and publish the npm ??

[scsper]

@lpw could you also update the readme?

[lpw]

@scsper updated README

[theogravity]

I've incorporated this PR into an improved version of cerebro:

https://github.com/theogravity/configurity