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
Engine: convenience http transport for simple remote job execution
Cleanup version introspection

* Unify version checking code into version.go
* Make 'version' available as a job in the engine
* Use simplified version checking code when setting user agent for registry client.
Port 'docker version' to the engine API
Fix #1229. Update titles, fix some wrapping.
Make the Ambassador container explicit.
Apply Sven's suggestions.
Merge pull request #3119 from shykes/engine-version

Port 'docker version' to the engine API
Merge pull request #3103 from metalivedev/1229-titleactions

Update "Use" titles to be action-oriented
don't open bind mounted files/dirs to get Stat, use os.Lstat
Merge pull request #3152 from daniel-garcia/3129_dont-open-bindmounted-files

don't open bind mounted files/dirs to get Stat, use os.Lstat
Merge pull request #3113 from shykes/engine-export

Move 'docker export' to the engine API