Fix typos in a various docs

* Change 'Controler' to 'Controller'
* 'build and storage' -> 'build and store'
* /usr/lib/docker -> /var/lib/docker
* xd -> xz
We use Atomic Hst as the term for the minimal OS
Fix url in README

The url in the 'Initial setup' section of the README is inaccessible
for most. Change to the GitHub url.
Merge pull request #39 from bcrochet/url-fix

Fix url in README
adding why project atomic post
Streamline the preservation of /var/lib/docker

There's no reason to copy and then remove, just makes the user wait longer to get going.
Merge pull request #40 from krujos/master

Streamline the preservation of /var/lib/docker
made some more friendly instructions to get started
Fix small error
oops we already have a quickstart guide, link to that instead
Merge branch 'master' of github.com:projectatomic/atomic-site