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)
Use https://get.docker.io/ubuntu consistently

The install script (on https://get.docker.io/) installs an APT sources.list
entry referencing an HTTPS repository, and takes care of installing the
apt-transport-https package. However, the Debian/Ubuntu specific installation
script (on https://get.docker.io/ubuntu) used an HTTPS repository but without
installing that package, causing the installation to fail on some platforms.

This will use HTTPS everywhere, and updates the documentation accordingly.

Docker-DCO-1.1-Signed-off-by: Jérôme Petazzoni <jerome@docker.com> (github: jpetazzo)

Docker-DCO-1.1-Signed-off-by: Jérôme Petazzoni <jerome@docker.com> (github: jpetazzo)
Merge pull request #4715 from sebsto/patch-1

Include instruction for AMI 2014.03
Merge pull request #4997 from jpetazzo/apt-should-always-use-https

Use https://get.docker.io/ubuntu consistently
add some more text to the cli docs

Docker-DCO-1.1-Signed-off-by: Sven Dowideit <SvenDowideit@fosiki.com> (github: SvenDowideit)