Add helper function to define environment variables with defaults
Add helper function to parse environment variable urls into resources
Set default database encoding to utf8
Allow setting log output path via LOG_PATH environment variable
Allow specifying database configuration via DATABASE_URL env variable
Allow overriding caching engine with MEMCACHED_URL and REDIS_URL env variables
Fix issue with MEMCACHED_URL vs DATABASE_URL
Add extra configuration for buildpack
Add instructions for heroku use