[REEF-36] Remove duplicated binding of ManagerName

Currently RemoteConfiguration.ManagerName can be bound in either Client or Launcher.
For submission path that generates a static driver.config and then submits job remotely through REST api, it will cause duplicated binding.
This commit removes the binding in client and adds a default value to be safe.

JIRA: https://issues.apache.org/jira/browse/REEF-36

Author:    Yingda Chen <ydchen@gmail.com>

Closes #21