Restore the information of Parameters in `Program.clone()`

[reyoung]

Paddle/python/paddle/v2/fluid/framework.py

Lines 487 to 492 in d883547

	def clone(self):
	p = Program()
	p.desc = core.ProgramDesc(self.desc)
	p.blocks = [Block(p, i) for i in xrange(self.desc.num_blocks())]
	p.sync_with_cpp()
	return p

The Program.clone only clone the variables and ops in the program into a new program. However, the information of Parameter is not clone.

So we need restore the information of Parameters.