Support hairpin NAT without going through docker server

Hairpin NAT is currently done by passing through the docker server.  If
two containers on the same box try to access each other through exposed
ports and using the host IP the current iptables rules will not match the
DNAT and thus the traffic goes to 'docker -d'

This change drops the restriction that DNAT traffic must not originate
from docker0.  It should be safe to drop this restriction because the
DOCKER chain is already gated by jumps that check for the destination
address to be a local address.

Docker-DCO-1.1-Signed-off-by: Darren Shepherd <darren.s.shepherd@gmail.com> (github: ibuildthecloud)
Resync the DCO text with upstream at http://developercertificate.org/

```
Everyone is permitted to copy and distribute verbatim copies of this
license document, but changing it is not allowed.
```

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Add authenticated TLS support for API

Docker-DCO-1.1-Signed-off-by: Johannes 'fish' Ziemke <github@freigeist.org> (github: discordianfish)
Add proper support for relative WORKDIR instructions

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Include instruction for AMI 2014.03

Include instructions to install Docker from Amazon's Software Repository on new AMI 2014.03 (Release Candidate)

Docker-DCO-1.1-Signed-off-by: Sebastien Stormacq <sebastien.stormacq@gmail.com> (github: sebsto)
add softlayer installation instructions

Docker-DCO-1.1-Signed-off-by: Andrea Turli <andrea.turli@gmail.com> (github: andreaturli)
address comments from @jamtur01

Docker-DCO-1.1-Signed-off-by: Andrea Turli <andrea.turli@gmail.com> (github: andreaturli)
Improve WORKDIR test to cover more edge cases

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Add some documentation about relative WORKDIR values

Docker-DCO-1.1-Signed-off-by: Andrew Page <admwiggin@gmail.com> (github: tianon)
Prevent dynamic allocation of previously allocated ports

Docker-DCO-1.1-Signed-off-by: Andy Kipp <andy@rstudio.com> (github: kippandrew)
Better test error message

Docker-DCO-1.1-Signed-off-by: Andy Kipp <andy@rstudio.com> (github: kippandrew)
Be more explicit in finding next port to allocate

Docker-DCO-1.1-Signed-off-by: Andy Kipp <andy@rstudio.com> (github: kippandrew)
Add err checks for port allocator tests

Docker-DCO-1.1-Signed-off-by: Andy Kipp <andy@rstudio.com> (github: kippandrew)
libcontainer/network: add netns strategy

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)
libcontainer/nsinit/init: move mount namespace after network

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)
libcontainer: goimports

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)
libcontainer: remove duplicate imports

Docker-DCO-1.1-Signed-off-by: Johan Euphrosine <proppy@google.com> (github: proppy)
use this horrible complex bit of shell to make sure that curl doesn't hand the poor user a broken docker client

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@fosiki.com> (github: SvenDowideit)
mention the tgz - other people might like to know

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@fosiki.com> (github: SvenDowideit)
Merge pull request #4727 from andreaturli/master

add softlayer installation instructions