no error handling when changing state

[kmaehashi]

No error handling when changing the Controller status.

For example, when save method is called,

• change state from Wait to Saving
• do save action
• change state from Saving to Wait

When errors occur in the save action, the state does not go back to Wait state. As a result, save cannot be called anymore for that model.

https://github.com/jubatus/jubatus-on-yarn/blob/v1.0.0/jubatusonyarn/jubatus-on-yarn-container/src/main/scala/us/jubat/yarn/container/ContainerController.scala#L96-L117