README: Add build status of master branch

Author: Stefan Nothaas

README.md

@@ -1,5 +1,6 @@
 # DXMon
 
+[![Build Status](https://travis-ci.org/hhu-bsinfo/dxmon.svg?branch=master)](https://travis-ci.org/hhu-bsinfo/dxmon)
 [![Build Status](https://travis-ci.org/hhu-bsinfo/dxmon.svg?branch=development)](https://travis-ci.org/hhu-bsinfo/dxmon)
 
 DXMon is a standalone monitoring-framework for Linux but also part of the distributed In-Memory key-value storage [DXRAM](https://github.com/hhu-bsinfo/dxram).
@@ -45,4 +46,4 @@ An illustration is shown below for clarification:
 
 Copyright (C) 2018 Heinrich-Heine-Universitaet Duesseldorf, 
 Institute of Computer Science, Department Operating Systems. 
-Licensed under the [GNU General Public License](LICENSE).
+Licensed under the [GNU General Public License](LICENSE).