fix(builder): retrieve process types from slugbuilder's Procfile
fix(builder): retrieve process types from slugbuilder's Procfile

/bin/release was unofficially deprecated for declaring default process
types a while back, which is why some buildpacks don't supply any
default process types in /bin/release. Instead, the buildpack will
generate a Procfile if none is supplied.

deis/workflow,deis/workflow,deis/workflow