Rename namespace class to {package.name}Package

Conflicts:

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

compiler/testData/compileJavaAgainstKotlin/method/QExtendsString.java

@@ -2,6 +2,6 @@ class Question {
     // id2 is to prevent java type parameter type inference
     static <T> T id2(T p) { return p; }
     {
-        String s = id2(namespace.id(null));
+        String s = id2(_DefaultPackage.id(null));
     }
 }