Streamline tutorial docs

Fixes #634 
Replaces repetitive tutorials with an "Examples" section in "Getting Started", with much simplified structure and tutorials replaced with more minimal example Flocker config files and instructions.
I'm unclear as to whether there is a desire for these `vagrant up` instructions to be left in each of the examples documents, as the examples index page links to the MongoDB setup instructions and states that the deployment configs in these examples are intended to be used with those VMs. But equally, much as the aim of this issue is to streamline these examples and slim them down from full-on tutorials, there is a good possibility someone will jump straight in to one of these documents and without this section, the first thing they'll see are the SSH instructions below to IP addresses they might not have running, as a result of having not followed the Vagrant setup previously.