Use "PyArray_Transpose" in gemm implementation

Add a test to test_blas.py:TestBlasStrides to check
is gemm works well with non-contiguous matrices
(A,B,C are all passed as non-contiguous).

All tests passed ! Recall: these are the tests executed:

theano-cache purge && THEANO_FLAGS=blas.ldflags= nosetests theano/tensor/nnet/tests/test_abstract_conv.py:TestAbstractConvNoOptim
theano-cache purge && THEANO_FLAGS=blas.ldflags= nosetests theano/tensor/nnet/tests/test_abstract_conv.py:TestBilinearUpsampling
theano-cache purge && THEANO_FLAGS=blas.ldflags= nosetests theano/tensor/nnet/tests/test_abstract_conv.py:TestCorrConv2d
theano-cache purge && THEANO_FLAGS=blas.ldflags= nosetests theano/tensor/nnet/tests/test_abstract_conv.py:TestCorrConv3d
theano-cache purge && THEANO_FLAGS=blas.ldflags= nosetests theano/tensor/nnet/tests/test_abstract_conv.py:TestCpuConv2d
theano-cache purge && THEANO_FLAGS=blas.ldflags= nosetests theano/tensor/nnet/tests/test_abstract_conv.py:TestCpuConv3d
theano-cache purge && THEANO_FLAGS=blas.ldflags= nosetests theano/tensor/tests/test_blas_c.py
theano-cache purge && THEANO_FLAGS=blas.ldflags= nosetests theano/tensor/tests/test_blas.py
theano-cache purge && THEANO_FLAGS=blas.ldflags= nosetests theano/tensor/tests/test_blas_scipy.py
theano-cache purge && THEANO_FLAGS=optdb.max_use_ratio=10,blas.ldflags= nosetests theano/tensor/nnet/tests/test_corr3d.py
theano-cache purge && THEANO_FLAGS=optdb.max_use_ratio=7,blas.ldflags= nosetests theano/tensor/nnet/tests/test_corr.py