provision/docker: do not update unamed containers in scheduler

This is a preparation for #874. We will create a container that contains
the content of the uploaded archive, and save it to a specific
directory. Later we will use the archive url approach (using file://
scheme) to deploy the application.
provision: add UploadDeployer

This is a provisioner that can deploy uploaded files.

Related to #874.
provision/docker: prepare deploy to receive the image externally

Being able to receive the image like this enables us to generate a new
image before running archiveDeploy. This is exactly what we're doing for
app: add "File" to DeployOptions

Related to #874.
app, provision/docker: add support for the UploadDeployer

Related to #874.