Allow devices to be added to a deployment when they have no firmware yet

[joshk]

Currently, devices can only be added to a deployment when their aarch and platform are known, which happens when they have connected to Nerves Hub for the first time (and thus send over their firmware information)

I believe it would be a better UI experience to list all deployments, and include in the drop down the aarch and platform of the deployment, allowing for the device to be added to the deployment, and instead add a note under the dropdown or a flash message that the device will be removed from the deployment upon connection if the aarch and platform of the device doesn't match.

This feels like a nicer user experience as a device can be manually added, if it be via api or UI, and placed in a deployment (if tags aren't used for matching). If we don't allow this then we require the device to connect, which can remove users from there flow of learning the system.