ROC makes an assumption about name of remote

[wsromek]

It would be beneficiary to be able to set name of currently used remote.

(for example, our team uses origin to describe private fork, while central repo is called upstream - we would not like to have to change our naming patterns only to use storybook).

https://github.com/rocjs/roc-repo/blob/master/extensions/roc-plugin-repo-react/src/commands/storybook.js#L40

https://www.npmjs.com/package/gh-pages#optionsrepo