Modify for Python 3.x

This reverts commit 466dcd4f.

This reverts commit 1712a117.

Remove dependencies incompatible with Python 3

Removed futures and argparse since they are not available on Pypi for Python 3+

Fix from_networkx()

nodes_iter() of NetworkX since v2.0 is outdated

Remove dead link to documentation in README.rst and more neatness

Fix number_of_nodes()

order() is a method of the class Graph

Make process pool optional for loading adjacency lists

Based on time check from @ozlemmuslu, the speed-up is negligible for multiprocessing. I would guess this is due to the overhead in spawning new processes and pipes.

References #68

Compatibility with python3 (3.4.5)

A minor fix.

1. Add a section on evaluating DeepWalk on the classical BlogCatalog dataset;
2. Indicate that the current version of DeepWalk is based on a newer version of gensim.

Updating deepwalk to use latest versions of dependencies gensim and sklearn.

* Compatability with newest gensim and sklearn.
* Modify requirements.txt.

Fix the usage of the psutil API

Normalizing the embeddings by L2 norm reduces the quality, therefore, we disable the gensim option norm_only.