Skip javadoc generation for org.eclipse.jgit.http.test

This fixes the error the javadoc plugin raises when generating the maven
site for this bundle.

Change-Id: I72026aa33be86960747a246af4a70f6a91b40102
Signed-off-by: Matthias Sohn <matthias.sohn@sap.com>

org.eclipse.jgit.http.test/pom.xml

@@ -60,7 +60,9 @@
   <description>
     Tests for the HTTP transport.
   </description>
-
+  <properties>
+      <maven.javadoc.skip>true</maven.javadoc.skip>
+  </properties>
   <dependencies>
     <dependency>
       <groupId>junit</groupId>