fixes #2671, add support for bind mounting individual files in to containers, rebases of #1757 #2301
check on the client side that there is a Dockerfile, so we don't upload a huge stack of files, only to realise we can't do anything
Make docker build return exit code of build step

If a command during build fails, `docker build` now returns with
the exit code of that command.

This makes it necessary to change the build api endpoint to
return a json object stream.
Merge pull request #2206 from discordianfish/1150-build-return-exit-code

Make docker build return exit code of build step
Merge pull request #2775 from daniel-garcia/2671-bindmount_files

fixes #2671, add support for bind mounting individual files in to contai...
Merge pull request #2984 from SvenDowideit/2319-build-check-for-dockerfile

check on the client side that there is a Dockerfile
Merge remote-tracking branch 'docker/master' into dev