pre-pysal integration updates

[vidal-anguiano]

This pull request covers most of the updates that were discussed during the week of May 11th and includes:

• flatten file structure to get rid of the raam, fca, weights, datasets, and util folders
• collapse fca1-3.py into a single fca.py file
• get rid of access.set_cost and access.set_cost_neighbors from api and create property setters and getters for default_cost and default_cost_neighbors
• updated access.euclidean_distance to access.create_euclidean_distance, and same for access.euclidean_distance_neighbors