fix ordering classloader

If I run standalone server, occur this error. So I fixed.

$ mvn exec:java -Dexec.mainClass="org.usergrid.standalone.ServerLoader"

[INFO] --- exec-maven-plugin:1.2.1:java (default-cli) @ usergrid-standalone ---
java.lang.ClassNotFoundException: Failure to load: org.usergrid.standalone.Server
at com.jdotsoft.jarloader.JarClassLoader.loadClass(JarClassLoader.java:895)
at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
at com.jdotsoft.jarloader.JarClassLoader.invokeMain(JarClassLoader.java:770)
at org.usergrid.standalone.ServerLoader.main(ServerLoader.java:26)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.codehaus.mojo.exec.ExecJavaMojo$1.run(ExecJavaMojo.java:297)
at java.lang.Thread.run(Thread.java:680)