Automated merging for conda-forge feedstock

[jGaboardi]

New functionality in conda-forge allows for the automated merging of passing PRs in a package's feedstock. It is enabled through the opening of an issue with a specific copy/pasted message. See these issues in the mapclassify and spaghetti feedstocks for examples.

[jGaboardi]

See also this comment from @ocefpaf regarding some additional syntax in PACKAGE-feedstock/recipe/meta.yaml.

test:
  commands:
    - pip check
  requires:
    - pip