Add missing XML Schema reference

Author: garydgregory

src/assembly/bin.xml

@@ -14,7 +14,9 @@ Licensed to the Apache Software Foundation (ASF) under one or more
  See the License for the specific language governing permissions and
  limitations under the License.
 -->
-<assembly>
+<assembly xmlns="http://maven.apache.org/ASSEMBLY/2.2.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/ASSEMBLY/2.2.0 http://maven.apache.org/xsd/assembly-2.2.0.xsd">
     <id>bin</id>
     <formats>
         <format>tar.gz</format>

src/assembly/src.xml

@@ -14,7 +14,9 @@ Licensed to the Apache Software Foundation (ASF) under one or more
  See the License for the specific language governing permissions and
  limitations under the License.
 -->
-<assembly>
+<assembly xmlns="http://maven.apache.org/ASSEMBLY/2.2.0"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/ASSEMBLY/2.2.0 http://maven.apache.org/xsd/assembly-2.2.0.xsd">
   <id>src</id>
   <formats>
     <format>tar.gz</format>