pass --change changes to the commit job

Docker-DCO-1.1-Signed-off-by: Daniel, Dao Quang Minh <dqminh89@gmail.com> (github: dqminh)
build_config job: parse dockerfile ast into config

Instead of building the actual image, `build_config` will serialize a subset of
dockerfile ast into *runconfig.Config

Docker-DCO-1.1-Signed-off-by: Daniel, Dao Quang Minh <dqminh89@gmail.com> (github: dqminh)
support `changes` in commit job

In addition to config env, `commit` now will also accepts a `changes` env which
is a string contains new-line separated Dockerfile instructions.
`commit` will evaluate `changes` into `runconfig.Config` and merge it with
`config` env, and then finally commit a new image with the changed config

Docker-DCO-1.1-Signed-off-by: Daniel, Dao Quang Minh <dqminh89@gmail.com> (github: dqminh)
instantiate the builder job in commit integration tests

Docker-DCO-1.1-Signed-off-by: Daniel, Dao Quang Minh <dqminh89@gmail.com> (github: dqminh)
Merge remote-tracking branch 'dqminh/docker-commit-change' into import_change_option

Conflicts:
	api/client/commands.go
	api/server/server.go
	builder/job.go
pllm

Signed-off-by: Tomáš Hrčka <thrcka@redhat.com>

end