Migrate launch modal

1. Converted the Instance Launch modal to use Flex flow.
2. Broke out Instance Launch modal into multiple files and allowed it to be a root component, letting it specify what data it needs and showing a spinner until it has that data.
3. Renamed componentDidUnmount to componentWilUnmount in multiple files.  React looks for the componentWilUnmount method, so many components weren't unmounting properly.
4. Removed the InstanceController and some of the dependencies on ProfileController; most of the controllers have been migrated to Actions/Stores, but there are still a few left.
5. SizeStore now lazy loads.
6. Changed the way the Launch Modal requires the user to enter all information before launching.  Instead of showing a second screen w/ the missing required fields and redirecting the user back, the launch button is simply disabled while required information is missing.  It's not great though - the button coloring is inconsistent (light blue instead of light green), and it might be better to highlight the missing fields with a message or mark them as required.  But it works reliably and the other screens are a higher priority right now...I'll change it later.