Correctly parsing verbose flag in AppScalefile

Prior to this pull request, users could set "verbose: False" in their AppScalefile and we would still add the --verbose flag when running AppScale. This was because we were merely checking for the existence of the verbose flag in the AppScalefile, and not checking to see if it was actually set to True. This pull request remedies that oversight.

Accidentally forked this off of the EC2_SECRET_KEY in AppScalefile branch, so merge that branch in before this one.