fix use np.array.all() instead of Python all()

[pablogventura]

Fix this error using Numpy when i call to is_constant in deutsch jozsa:

`/usr/local/lib/python2.7/dist-packages/grove/deutsch_jozsa/deutsch_jozsa.pyc in is_constant(self, cxn, bitstring_map) 57 # We are only running a single shot, so we are only interested in the first element. 58 bitstring = np.array(returned_bitstring, dtype=int) ---> 59 constant = all([bit == 0 for bit in bitstring]) 60 return constant 61

ValueError: The truth value of an array with more than one element is ambiguous. Use a.any() or a.all() `

Now it uses all function from Numpy instead of builtin all function.