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
Add proper bash completion for "docker push"
use less reflection in command line method invocation
Adding more tests around `auth.ResolveAuthConfig`

mostly because I've been failing at getting docker `0.6.2` working with
docker-registry `0.6.0` with regard to login and push.  I suspect there
may be some mismatched expectations between `auth.ResolveAuthConfig` and
`registry.ResolveRepositoryName`, but I haven't done enough research or
experimentation to think it's anything more than user error.  More tests
are good, no?
Fix #1993: add explanation for export restrictions
lxc: Allow set_file_cap capability in container

This means you're able to set the bits for capabilities on files
inside the container. This is needed for e.g. many fedora packages
as they use finegrained capabilities rather than setuid binaries.

This is safe as we're not adding capabilities really, since the
container is already allowed to create setuid binaries. Setuid
binaries are strictly more powerful that any capabilities (as root implies
all capabilities).

This doesn't mean the container can *gain* capabilities that it
doesn't already have though. The actual set of caps are strictly
decreasing.
Configured FPM to make /etc/init/docker.conf a config file.
Hint for Remote API doc details in header links
Used tabs for alignment when I should've used spaces. Fixed.
Clearly point at detailed docs
add .dockercfg doc
Fix the attach behavior with -i
Fix #1969 formatting, add information about multiline json
Merge pull request #2034 from metalivedev/1969-cherrypick-fixcommitformat

Fix #1969 formatting, add information about multiline json
Added more context.
Changes to a new style for the docs. Includes version switcher.

* added link to edit on GitHub
* Changed image source on homepage
* Made some changes to the structure, added the ability to have l3 navigation. Added warning, note and other styles.
* Fixed an image link, removed the .. :content: links because they were quicky and didn't look good, added pagelinks to current page of other versions.
* Moved the remote client api's to their own doc
Add contrib/mkimage-centos.sh back (from #1621), and associated documentation link
Merge pull request #2025 from dotcloud/2020_add_dockercfg_doc

add .dockercfg doc
Merge pull request #1995 from dotcloud/fix_attach_2

Fix the attach behavior with -i