Implement tuple.__add__, dict.__contains__ and builtin id() function

The __contains__ method crashes the runtime when using the 'dict' type directly

eg.  
1 in dict()  # fails deep down in stl

Also for id() I took the cpython approach by casting the address of the Box* to i64.  I noticed thats an llvm type, is that correct?
 
Hmm can we add some statements like `print id(x) == id(x)`, `print id(x) == id(y)`, etc -- while it's pretty simple, I think it'd be nice to test some of the properties (even if straightforward) in addition to just making sure it doesn't fail.