resolved plugin failing to run if ['docs']['count'] doesn't exist under ...

...['indices'].  The following error was being thrown:
```
{:snapshot=>"",
 :errors=>
  [{:created_at=>"2013-07-25 17:26:19",
    :local_filename=>nil,
    :plugin_id=>5924221,
    :origin=>nil,
    :fields=>
     {:body=>
       "NoMethodError: undefined method `[]' for nil:NilClass\nelasticsearch node status:39:in `build_report'\n/var/lib/gems/1.8/gems/scout-5.6.9/bin/../lib/scout/plugin.rb:220:in `run'\n/var/lib/gems/1.8/gems/scout-5.6.9/bin/../lib/scout/server.rb:398:in `process_plugin'\n/usr/lib/ruby/1.8/timeout.rb:62:in `timeout'\n/var/lib/gems/1.8/gems/scout-5.6.9/bin/../lib/scout/server.rb:397:in `process_plugin'\n/var/lib/gems/1.8/gems/scout-5.6.9/bin/../lib/scout/server.rb:301:in `run_plugins_by_plan'\n/var/lib/gems/1.8/gems/scout-5.6.9/bin/../lib/scout/server.rb:299:in `each'\n/var/lib/gems/1.8/gems/scout-5.6.9/bin/../lib/scout/server.rb:299:in `run_plugins_by_plan'\n/var/lib/gems/1.8/gems/scout-5.6.9/bin/../lib/scout/command/run.rb:51:in `run'\n/var/lib/gems/1.8/gems/scout-5.6.9/bin/../lib/scout/command.rb:164:in `dispatch'\n/var/lib/gems/1.8/gems/scout-5.6.9/bin/scout:9",
      :subject=>"Plugin failed to run"}}],
```