Improved CI support for the Deployments API

Today we're making a few minor changes to the Deployments API preview. With the introduction of combined statuses in a recent update, we noticed a few inconsistencies with the API that we'd like to remedy.

We're introducing a new parameter called required_contexts. This parameter accepts an array of named commit status contexts that are ensured to be in a "success" state before the deployment is created. This allows you to verify that more than one system verified your code before you deploy it.

We've removed support for the force parameter. The force parameter existed to bypass both the auto-merge and commit status checks. The same behavior can now be accomplished by setting auto_merge and required_contexts appropriately.

We're also setting a context for all commit statuses. If a commit status is created without a context, we'll now set it to the string "default".

If you have any questions or concerns, drop us a line.