README : add jenkins build status links

So that in the README on github the status of the
builds is displayed.

Author: datalogics-bhaugen

README.md

@@ -2,3 +2,8 @@ SDKLauncher-iOS
 ===============
 
 A small iOS application to serve as a launcher/testbed for the Readium SDK.
+
+## Jenkins build status
+
+* master [![Build Status](http://jenkinsmaster.datalogics-cloud.com:8080/buildStatus/icon?job=Readium-SDK-Launcher-iOS-master)](http://jenkinsmaster.datalogics-cloud:8080/view/Readium-Launcher/job/Readium-SDK-Launcher-iOS-master/)
+* develop [![Build Status](http://jenkinsmaster.datalogics-cloud.com:8080/buildStatus/icon?job=Readium-SDK-Launcher-iOS-develop)](http://jenkinsmaster.datalogics-cloud:8080/view/Readium-Launcher/job/Readium-SDK-Launcher-iOS-develop/)