Add support for type parameters for classes

Allow type parameters for class, ie `class Foo<Bar, Baz>`

/cc @vojtajina 
E is the above example is an arbitrary identifier, could be anything `class Value<MySuperTypeName>`. 

The type will only be known at runtime `new Value<number>();`

Note: TS support constraints (which does not seem to implemented in Traceur `class Value<MySuperTypeName extends Type>`. When/If this comes to Traceur, we should validate "Type".