Docs: use Oracle Java by default

 Installing Oracle JVM is as easy as:

 ```
 echo debconf shared/accepted-oracle-license-v1-1 select true | \
   sudo debconf-set-selections && echo debconf shared/accepted-oracle-license-v1-1 seen true | \
   sudo debconf-set-selections && sudo add-apt-repository ppa:webupd8team/java && sudo apt-get update && sudo apt-get install oracle-java7-installer
 ```

 See http://www.webupd8.org/2012/01/install-oracle-java-jdk-7-in-ubuntu-via.html

 Closes #19.
Docs: Generating ssh keys

There's a much better documentation (including using existing OpenSSH keys like most of us already have for git) on the Azure docs, e.g.:

http://azure.microsoft.com/en-us/documentation/articles/linux-use-ssh-key/

Closes #18.