Not complete effort to make the back button work better
Catching the popstate event seems like a good idea, but the
flow logic is broken. Rethink.
Merge branch 'master' into fix-back-button

Conflicts:
	webapp/netlog.html
Fix bugs for state management.
Back button now basically working.
One bug, if the user chooses not to upload and then drops in
a couple of files, back doesn't redraw the old non-uploaded state.