OpenStack backend doesn't support the stop command properly

[rtyler]

-> % blimpy stop
>> Stopping: bob-dev,/home/tyler/.rvm/gems/ruby-1.9.3-p0@bob/gems/blimpy-0.6.4/lib/blimpy/box.rb:97:in `stop': undefined method `stop' for #<Fog::Compute::OpenStack::Server:0x00000001c57f28> (NoMethodError)
        from /home/tyler/.rvm/gems/ruby-1.9.3-p0@bob/gems/blimpy-0.6.4/lib/blimpy/fleet.rb:152:in `block in stop'
        from /home/tyler/.rvm/gems/ruby-1.9.3-p0@bob/gems/blimpy-0.6.4/lib/blimpy/fleet.rb:149:in `each'
        from /home/tyler/.rvm/gems/ruby-1.9.3-p0@bob/gems/blimpy-0.6.4/lib/blimpy/fleet.rb:149:in `stop'
        from /home/tyler/.rvm/gems/ruby-1.9.3-p0@bob/gems/blimpy-0.6.4/lib/blimpy/cli.rb:103:in `stop'
        from /home/tyler/.rvm/gems/ruby-1.9.3-p0@bob/gems/thor-0.16.0/lib/thor/task.rb:27:in `run'
        from /home/tyler/.rvm/gems/ruby-1.9.3-p0@bob/gems/thor-0.16.0/lib/thor/invocation.rb:120:in `invoke_task'
        from /home/tyler/.rvm/gems/ruby-1.9.3-p0@bob/gems/thor-0.16.0/lib/thor.rb:275:in `dispatch'
        from /home/tyler/.rvm/gems/ruby-1.9.3-p0@bob/gems/thor-0.16.0/lib/thor/base.rb:425:in `start'
        from /home/tyler/.rvm/gems/ruby-1.9.3-p0@bob/gems/blimpy-0.6.4/bin/blimpy:20:in `<top (required)>'
        from /home/tyler/.rvm/gems/ruby-1.9.3-p0@bob/bin/blimpy:19:in `load'
        from /home/tyler/.rvm/gems/ruby-1.9.3-p0@bob/bin/blimpy:19:in `<main>'