Rename namespace class to {package.name}Package

Conflicts:

	compiler/jet.as.java.psi/src/org/jetbrains/jet/asJava/JavaElementFinder.java

compiler/testData/compileJavaAgainstKotlin/method/Void.java

@@ -1,5 +1,5 @@
 class Void {
     {
-        namespace.f();
+        _DefaultPackage.f();
     }
 }