hcluster check AMIs but if there is no AMI

[jhho]

lib/hcluster.rb:328:in 'find_owned_image' from ~/hbase-ec2/lib/hcluster.rb:234:in 'create_image' from recipes/create_image.rb:14

[ekoontz]

More details: http://pastebin.com/FpeC2wue

joshua@localhost:~/hadoop/ec2-1/hbase-ec2$ ruby recipes/create_image.rb
using /home/joshua/.ec2/root.pem as ssh key.
/home/joshua/hadoop/ec2-1/hbase-ec2/lib/hcluster.rb:346:in `describe_images': undefined method `[]' for nil:NilClass (NoMethodError)
    from /home/joshua/hadoop/ec2-1/hbase-ec2/lib/hcluster.rb:328:in `find_owned_image'
    from /home/joshua/hadoop/ec2-1/hbase-ec2/lib/hcluster.rb:234:in `create_image'
    from recipes/create_image.rb:14

[ekoontz]

proposed fix: http://github.com/ekoontz/hbase-ec2/commit/49dd6ac0dda0eca2722b8efb727a275fe6a2fdf5