comply with package format2 xsd (#83)

package.xml

@@ -7,13 +7,14 @@
     The class_loader package is a ROS-independent package for loading plugins during runtime and the foundation of the higher level ROS "pluginlib" library. class_loader utilizes the host operating system's runtime loader to open runtime libraries (e.g. .so/.dll files), introspect the library for exported plugin classes, and allows users to instantiate objects of said exported classes without the explicit declaration (i.e. header file) for those classes.
   </description>
   <maintainer email="mikael@osrfoundation.org">Mikael Arguedas</maintainer>
-  <author>Mirza Shah</author>
   <license>BSD</license>
 
   <url type="website">http://ros.org/wiki/class_loader</url>
   <url type="bugtracker">https://github.com/ros/class_loader/issues</url>
   <url type="repository">https://github.com/ros/class_loader</url>
 
+  <author>Mirza Shah</author>
+
   <buildtool_depend version_gte="0.5.68">catkin</buildtool_depend>
 
   <build_depend version_gte="0.3.3">cmake_modules</build_depend>