Add API support for Issue Boards
Description
Issue Boards are mostly possible to recreate using existing APIs, we essentially use other components (Issues, Labels, and Label Priority) to construct the feature.
There is one thing not reproducible from the API, however, and that's the ability to pull down the labels used in a project's Issue Board.
Proposal
The API should have the ability to GET /projects/:id/board.json (or something similar) which would return the list of labels used as "columns" or "lists" in the Board. When multiple boards are supported for a project, this endpoint would also provide a name/description, and anything else the boards may have.
For example this would return the UX, Frontend, and Backend labels:
It should also be possible to POST (or PUT?) to the board with a label ID to add a new list, as well as DELETE-ing to remove a list (or board once multiple boards are available).
I don't see too much use in adding other endpoints for issue boards since that'd just be repetitive, but maybe people disagree?