process http request for perf data logged from LoggingScope. Allow to access driver log files through http request.

This is to address issue REEF-29 https://issues.apache.org/jira/i#browse/REEF-29?filter=-1

Author: Julia Wang
email: jwang98052@yahoo.com
Merge branch 'juwang-perflog-http' of github.com:jwang98052/incubator-reef into juwang-perflog-http
[REEF-47]: Log the REEF Version in all processes.

The following changes are made to that end:

  * The new method `REEFVersion.logVersion()` is added which performs the
    actual logging.
  * On the client, this method is called in the constructor of
    `REEFImplementation`.
  * On the Driver and Evaluator, the method is called in the constructor of
    `LaunchClass`

Also, this removes the method `REEF.getVersion()` and its implementation in
`REEFImplementation` as that method wasn't used.

Related JIRAs:
  [REEF-47](https://issues.apache.org/jira/browse/REEF-47)

This is to closes #22

Author:    Markus Weimer <weimer@apache.org>
Merge branch 'master' into juwang-perflog-http