Switch to host naming

Servers concept will encompass custom cmd and labels. Host is just the IP address.

lib/tasks/mrsk/server.rake

@@ -5,7 +5,7 @@ namespace :mrsk do
     desc "Setup Docker on the remote servers"
     task :bootstrap do
       # FIXME: Detect when apt-get is not available and use the appropriate alternative
-      on(MRSK_CONFIG.servers) { execute "apt-get install docker.io -y" }
+      on(MRSK_CONFIG.hosts) { execute "apt-get install docker.io -y" }
     end
   end
 end