Add labelColor and icon query properties to http and runkit badge APIs

[evelynhathaway]

Currently the HTTP badges can return the following:

{
    subject: 'hello',
    status: 'world',
    color: 'blue'
}

But it would be cool to be able to have control over the labelColor and icon dynamically as well!

Use case: on my GitHub profile readme, I have on a custom status badge that takes my current project from a time tracking app. The label color would be nice to change when the project is active.

[amio]

That's a good idea 👍