Fix tycho version.

Signed-off-by: Greg Watson <g.watson@computer.org>
diff --git a/pom.xml b/pom.xml
index 121b64c..f5772fa 100644
--- a/pom.xml
+++ b/pom.xml
@@ -15,6 +15,7 @@
 
 	<properties>
 		<tycho-version>0.15.0</tycho-version>
+		<tycho-extras-version>0.15.0</tycho-extras-version>
 		<platform-version>4.2</platform-version>
 		<platform-site>http://download.eclipse.org/eclipse/updates/${platform-version}</platform-site>
 		<cdt-version>juno</cdt-version>