ported objmodel.cpp to use rewriter2 exclusively, deprecates rewriter1
removed rewriter1
fixed a bunch of bugs
got rid of 2s
Fix the dict() constructor

ie actually add one.  Before dict.__new__ would simply call
object.__new__ and return something that was very much not a dict :/
Merge branch 'master' of https://github.com/dropbox/pyston

Conflicts:
	src/runtime/dict.cpp
Merge pull request #113 from tjhance/rewriter2

Rewriter2
Merge remote-tracking branch 'upstream/master'
Modified dict tests

removed dict_contains.py
fixed merge miss in dict.cpp
XOR returned value from id function by constant