Rewrite pre_workshop page to focus on the VM method, copy Dan's VM setup instructions to new page
Merge pull request #139 from decklin/vm_setup

Rewrite pre_workshop page to focus on the VM method, copy Dan's VM setup instructions to new page
Installfest fixes
- added local links to OS sections
- added SublimeText 2 step
- added download vm image step
- added Chromebook step with info on Nitrous.io
- added link to ruby-lang.org install page for Linux, plus how to check if already installed
Rearranging the VM setup steps.  First make the folder, then go there in the command line, then run stuff.
Removed the instruction to install the box from a URL - use the file they downloaded ahead of time or ask for USB.
Put headings for each step, and broke it down into smaller steps.
Added reminders at the end for halting, starting, and connecting.
Fixed url markdown