Improve network performance for VirtualBox

Without those lines, VitrualBox machines are being very slow with all network operations (tested only in OS X Lion, but they are supposed to work everywhere). See https://github.com/mitchellh/vagrant/issues/1807
abord build if mergeConfig returns an error and fix duplicate error message
Merge pull request #2034 from metalivedev/1969-cherrypick-fixcommitformat

Fix #1969 formatting, add information about multiline json
Add test
add missing error check
added initial draft of the Docker infrastructure doc
Minor updates to postgresql_service.rst

I've added the steps that were missing/wrong for me when I went through this just now.
tell the new developer how they can replace the real docker binary with the one they've been hacking on (#2142)
testing, issue #1766: Add nightly release to docker-ci
testing, issue #1766: Upgrade tooling for Docker nightly release
testing infrastructure, issue #1766: Temporarily install docker with proper apparmor handling
testing infrastructure, issue #1766: Dockerize deployment of docker-ci
Merge pull request #1813 from doubleyou/patch-1

Improve network performance for VirtualBox
devmapper: Move all "raw" libdevmapper wrappers to devmapper.go

This separates out the DeviceSet logic a bit better from the raw
device mapper operations.

devicemapper: Serialize addess to the devicemapper deviceset

This code is not safe to run in multiple threads at the same time,
and neither is libdevmapper.

DeviceMapper: Move deactivate into UnmountDevice

This way the deactivate is atomic wrt othe device mapper operations
and will not fail with EBUSY if someone else starts a devicemapper
operation inbetween unmount and deactivate.

devmapper: Fix loopback mounting regression

Some changes were added to attach_loop_device which added
a perror() in a place that caused it to override errno so that
a later errno != EBUSY failed. This fixes that and cleans up
the error reporting a bit.

devmapper: Build on old kernels without LOOP_CTL_GET_FREE define
device-mapper: Move all devicemapper spew to log through utils.Debugf().
Clean up better from previous unit-test runs

This makes sure we unmount existing mounts (as well as removing the
devmapper devices), and it fails with proper logs rather than just
panic()ing.
Migrate AUFS containers to devmapper

Conflicts:
	hack/make.sh
	runtime.go
Verbose migration add warning for running container

Conflicts:
	hack/make.sh
	runtime.go
	runtime_test.go
Merge pull request #1823 from dotcloud/1766-nightly-release

testing, issue #1766: Add nightly release to docker-ci
Allow loopback and base fs sizes set by env var