Fixed free swap check right after creating swap file
Moved swap file creation up to just before hibernation
Deleted code that creates swap file. Replaced it with simple swap size check

While the code from the previous commit probably works, it appears
that hibernating to a swap file instead of a swap partition is harder
than I originally thought. Not sure why I didn't test this before writing
the code (or did I?). Uswsusp might be able to do it, but that requires
additional code, and testing. For now, I removed the swap file creation
code, replacing it with a simple check to see if we have enough swap
space to hibernate.