Update build to use Tycho 0.8

Change-Id: I99bac3376d9460ab94b548bd2f83be6fbc6ecbe3
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit.packaging/pom.xml

@@ -59,7 +59,7 @@
   <name>JGit Tycho Parent (Incubation)</name>
 
   <properties>
-    <tycho-version>0.7.0</tycho-version>
+    <tycho-version>0.8.0</tycho-version>
     <eclipse-site>http://download.eclipse.org/releases/galileo</eclipse-site>
   </properties>