if the AWS S3 bucket does not exist, create it

This makes the AWS S3 setup dead simple: just put in a awsbucket name of
your choosing, set the AWS credentials, and it'll do the rest, whether the
bucket exists already or not.  S3 buckets are trivial to delete too, in
case of error: `s3cmd rb s3://mybadbucketname`.

setup.py

@@ -32,7 +32,7 @@ setup(name='fdroidserver',
         'paramiko',
         'PIL',
         'python-magic',
-        'apache-libcloud >= 0.5',
+        'apache-libcloud >= 0.14.1',
         ],
       classifiers=[
         'Development Status :: 3 - Alpha',