pantries should have a pantry.md or similar for info + config

[elyseholladay]

A pantry should know some things about itself (its name, a description, dependencies if any, or other config) and a developer should be able to see those things in a preview (e.g. Bechamel).

Following ingredient.md we may want to have a pantry.md or possibly just use a pantry's package.json for this information. It should be displayable in Bechamel.

This may also related to the webpack configs and specifying what framework/helpers/dependencies a pantry needs, see #10