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
These links to the "sub-pages" of the tutorial - the page names don't give any indication that they're part of a tutorial... I wonder if this use case - a number of separate pages that add up to a single tutorial - might warrant a subfolder to contain them, with a bit more thought put into resulting file names? Or perhaps investigate "collections" and the add-on that provides collection navigation?