Update orbit update site to 2018-12 M2

Signed-off-by: Ondrej Dockal <odockal@redhat.com>

pom.xml

@@ -24,7 +24,7 @@
 		<tychoExtrasVersion>${tycho-version}</tychoExtrasVersion>
 		<eclipse-target-site>http://download.eclipse.org/staging/2018-12/</eclipse-target-site>
 		<swtbot-update-site>http://download.eclipse.org/technology/swtbot/snapshots/</swtbot-update-site>
-		<eclipse-orbit-update-site>http://download.eclipse.org/tools/orbit/downloads/drops/S20181010170940/repository</eclipse-orbit-update-site>
+		<eclipse-orbit-update-site>http://download.eclipse.org/tools/orbit/S-builds/S20181031145145/repository/</eclipse-orbit-update-site>
 		<download-plugin-version>1.2.1</download-plugin-version>
 		<project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
 		<!-- In the update site's site/pom.xml (that calls jbosstools-maven-plugins/tycho-plugins/repository-utils)