Complete documentation of source code

[orsharir]

Many functions in the source code are left undocumented, and more importantly many "user-facing" api functions. The documentation should also follow best practices of each respective language, and document the role of each parameter. We should strive such that we can ran documentation generation tools on our code to have the API for using this library available online.

For python, you should follow the reStructuredText syntax, so that we would be able to use readthedocs.io (in the background, it is based on Sphinx). For C++, you should follow the Doxygen syntax.

[elhanan7]

@orsharir Is there a place where I can find documentation of the functionality of the mex and similarity layers?

[orsharir]

Part of it is simply our papers, and part is in caffe.proto.

[elhanan7]

I added initial documentation to the ops in mex_op.cpp and similarity_op.cpp. @orsharir Can you please review what I did? When we'll finish with doc for the cpp ops I will adapt them to the keras layers.