Use multiple columns

[blazeu]

As we can see from the screenshot in README.md, it has multiple columns, but our gh-board doesn't.

That is because ryanprior/gh-board uses hard-coded columns based on the issue labels.

And the original philschatz/gh-board uses regex based columns which also need a specific custom label to work. i.e. [columnNumber] [actualLabelName].

The columns should be configurable by the user and should have a default configuration of creating columns based on labels that is generally used in GitHub e.g. type/*, size/*, status/* and the default one that comes from GitHub. e.g. enhancement, bug, question.

[jayvdb]

This is likely blocked until https://github.com/coala/gh-board/issues/6 is done, otherwise we end up with a wildly divergent fork.