Added Version and Revision of Stratosphere in Webinterface

https://issues.apache.org/jira/browse/FLINK-946

![bildschirmfoto 2014-06-20 um 14 43 26](https://cloud.githubusercontent.com/assets/5738978/3340103/82d0485e-f878-11e3-9d15-617102ea40a3.png)