Add py-redis as a requirement
Add settings for adjacency calculator to xsd file
Add settings for KeyValuStore to xsd file

A KeyValuestore (Redis) is required to run the adjacency calculator.
This commit adds support for adding this configuration to the
config.xml file.
Add instructions for installing redis-server
Add import of adjacency files to setup script

By default this will not run since most instances
will not have adjacency data currently.
Add adjacency calculator tests

These get skipped if the adjacency calculator is not
configured in settings.py
Add commands to write redis config to settings.py in set up
Add adjacency calculator to set of calculators

Adjacency calculator calculates average cost/travel/etc.
between all base geounits for a district and plan. It
assigns a score to a district that is the average adjacency
between all base geounits of a district or a normalized
score for an entire region/plan based on the individual
district scores and the average adjacency between all
base geounits for a region.

To speed up calculations and queries an in-memory key-value
store (Redis) is used to store adjacency data.
Refactor key generation for redis into a utility function
Add example settings required for Adjacency calculator
Add redis utility for generating keys
Merge pull request #442 from notthatbreezy/topic/adjacency-calculator

Topic/adjacency calculator