FLUID-5377: Converted Getting Started tutorial

Converted the getting started tutorial to markdown.
http://wiki.fluidproject.org/display/docs/Tutorial+-+Getting+started+with+Infusion

http://issues.fluidproject.org/browse/FLUID-5377
I have two proposals:

1) a Tutorials folder for all tutorials. Inside that folder, if a tutorial has multiple files, the root page is in the Tutorials folder and any other files are in a subfolder named for that tutorial. So for the getting started tutorial, we'd have:
    tutorials/
        GettingStarted.md
        gettingStarted/
            ModelComponents.md
            etc. 

2) Same as above, but no separate tutorials folder. Root page of a multi-page tutorial would go right in the root of the repo, but other pages would be in a  tutorial-named folder.

What do you think?