Add additional instructors.
Remove Michael due to time conflicts.
Add line break for readability.

The different versions were already on two lines in the source. I added the magic two spaces to the end of the first line to get a line break.
Update RailsInstaller download instructions.

The Rails Installer page no longer auto-selects a download or displays a "Download the kit" action.
One-time instructions for opening app from unidentified developer.

Instead of turning off Mac OS X Gatekeeper, use the context menu to open the app.
Add sponsor logos: RBM, Digital Lumens.