Make routes.cache loading more robust with class name change

[ngocdaothanh]

routes.cache loading is not retried when JSRoutesAction is renamed to JsRoutesAction:

java.lang.ClassNotFoundException: xitrum.routing.JSRoutesAction
    at java.net.URLClassLoader$1.run(URLClassLoader.java:202)
    at java.security.AccessController.doPrivileged(Native Method)
    at java.net.URLClassLoader.findClass(URLClassLoader.java:190)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:306)
    at java.lang.ClassLoader.loadClass(ClassLoader.java:247)
    at java.lang.Class.forName0(Native Method)
    at java.lang.Class.forName(Class.java:171)
    at xitrum.routing.RouteCollection$.xitrum$routing$RouteCollection$$getCacheSecsFromParent(RouteCollection.scala:72)
    at xitrum.routing.RouteCollection$$anonfun$fromSerializable$2$$anonfun$apply$22.apply(RouteCollection.scala:53)
    at xitrum.routing.RouteCollection$$anonfun$fromSerializable$2$$anonfun$apply$22.apply(RouteCollection.scala:52)
    at scala.collection.mutable.ResizableArray$class.foreach(ResizableArray.scala:59)
    at scala.collection.mutable.ArrayBuffer.foreach(ArrayBuffer.scala:47)
    at xitrum.routing.RouteCollection$$anonfun$fromSerializable$2.apply(RouteCollection.scala:52)
    at xitrum.routing.RouteCollection$$anonfun$fromSerializable$2.apply(RouteCollection.scala:51)
    at scala.collection.immutable.List.foreach(List.scala:318)
    at xitrum.routing.RouteCollection$.fromSerializable(RouteCollection.scala:51)
    at xitrum.Config$.routes$lzycompute(Config.scala:271)
    at xitrum.Config$.routes(Config.scala:269)
    at xitrum.Server$.start(Server.scala:48)
    at xitrum.Server$.start(Server.scala:21)
    at quickstart.Boot$.main(Boot.scala:7)
    at quickstart.Boot.main(Boot.scala)
    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)