Reformatted code, sobel convolution

Code has been reformatted such that namespaces and class visibility modifiers
create a new level of indentation.

First approach at a parallelized variant of convolution. No shared memory is
used so far. Implementation of convolution with sobel filters in preprocess
is present, but untested. Calculating the gradient strength still needs to
be done.
Gradient strength calculation, gpuImg->cpuImg

Added a kernel to compute the gradient strength and integrated it into the
computeGradientStrength method. Also wrote a method to move images from the GPU
to the CPU.
Merge branch 'master' of github.com:chris-code/cudaHough