Some initial edits

This is a big edit. Basically it removes a lot of repetitive content and cleans up some grammar, spelling and structure issues (use US English :)). It's not complete yet but should give a feel for how I'd like it to read. 

Some key points:

1. We need to tell a story about how and why of Docker. That story is currently:
  a. It's a framework
  b. It's designed to make development lifecycles/workflow and deployment awesome
2. Succinct. More succinct.
3. Use US English throughout.
4. There's too much exposition on non-Docker things - for example we tell people what a virtual machine is. I'd add some content back into that section but like 1-2 paragraphs that explain the differences between Docker and a VM without expositing on what a VM is.
5. We need to be more consistent on when and what we introduce as core concepts. You can see what I've tried to do that in the sections.

I've also wrapped and removed a lot of whitespace.

Docker-DCO-1.1-Signed-off-by: James Turnbull <james@lovedthanlost.net> (github: jamtur01)