Engine: don't log job stdout to engine stdout (it might be non-text output, for example tar data for 'export'
Engine: 'export' returns a raw archive of a container's filesystem
Merge pull request #3113 from shykes/engine-export

Move 'docker export' to the engine API
make docs is more consistent
Merge pull request #3159 from SvenDowideit/make-docs-consistency

Makefile: make docs is more consistent