gh-1816 PR with small fixes

Remove import of device_properties at the top of the file, as this break import of Theano when there is no GPU available.

This is needed for the new gpu op tests to pass.

Corrected check for whether cuda is active or not and compile only one addition kernel instead of many in the perform() method.

Mostly adapted Op and tests to new backend. TODO: Remove faulty python implementation from _dev20 version of op

Copied GpuAdvancedIncSubtensor1() and GpuAdvancedIncSubtensor1_dev() ops and their tests to sandbox/gpuarray

Fast rng mrg

Conflicts:
	theano/sandbox/rng_mrg.py
	theano/sandbox/test_rng_mrg.py

Corrected check for whether cuda is active or not and compile only one addition kernel instead of many in the perform() method.

Cuda ndarray fix

Speed up from 0.085s to 0.055s in mrg init.

Remove overflow and detect it if it happen again.