Rename namespace class to {package.name}Package

Conflicts:

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

compiler/testData/writeSignature/declarationSiteVariance/OutInInPosition.kt

@@ -1,6 +1,6 @@
 fun f(p: List<String>) {}
 
-// method: namespace::f
+// method: _DefaultPackage::f
 // jvm signature:     (Ljava/util/List;)V
 // generic signature: (Ljava/util/List<+Ljava/lang/String;>;)V
 // kotlin signature:  (Ljet/List<Ljava/lang/String;>;)V