Rename Python package framework.layers into fluid.layer

[wangkuiyi]

Current we create a layer by calling layers.fc:

Paddle/python/paddle/v2/framework/tests/test_fit_a_line.py

Lines 21 to 25 in 66d1c6c

	y_predict = layers.fc(input=x,
	size=1,
	act=None,
	program=program,
	init_program=init_program)

However, it should be layer.fc instead -- no s.

---

We are going to name the newly added features in python/paddle/v2/framework and related C++ code fluid. So we should rename python/paddle/v2/framework into python/paddle/v2/fluid.

[Yancey0623]

I will close this issue, python/paddle/v2/framework has already been move to python/paddle/fluid