Try to remove some shuffles in the apps

fix optimization twice error
It will only affect region map，we only evaluate expr in kws，map fusion will not be affect.

发自我的 iPhone

> 在 Sep 15, 2014，8:37 AM，Chien-Chin Huang <notifications@github.com> 写道：
> 
> In spartan/expr/map.py:
> 
> >    def _evaluate(self, ctx, deps):
> >      children = deps['children']
> >      child_to_var = deps['child_to_var']
> > -    op = self.op
> > +    self._evaluate_kw(self.op)
> But if you evaluate all the children here, doesn't this mean map fusion is useless?
> 
> —
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