REEF-34: Add convencience methods for command line parsing

This addresses [REEF-34](https://issues.apache.org/jira/browse/REEF-34) and adds the two methods mentioned.

Addressing the issues raised in the PR

  * Removed a bogus newline
  * Added a test for the new functionality

Added a missing licensing header

  * Renamed `CommandLineTest` to `TestCommandLine`
  * Moved the other named parameter from `TestCommandLine` into `NamedParameters`
  * Gave the named parameters in `NamedParameters` more descriptive names

Fixed a rename typo

This closes #11