Updated configuration steps.
Fixes and typos.
Added Redis server initialization.
Added Cache module and Redis implementation.

Add: CacheInterface that defines basic cach server functionality requirements.
Add: RedisCache - CacheInterface wrapper for Predis library.
Add: NullCache - dummy cache interface in case Redis server is offline!
Add: Cache server initialization in app.php
Added caching of Locale queries.
Added Redis hash get and set functionalities.
API now requires a X-Authorization HTTP header.
Only log query string if params are present.
Fixes in Redis cache server connection.

Fix: Use NullCache if Redis is disabled in config.php
Fix: Explicitly attempt to connect 'PredisClient::connect' when
initializing cache singleton.
Moved X-Authorization check in slim.before hook.
X-Authorization header scheme renamed to EAD-TOKENS
Added 'User-Agent' header validation.
Added Redis key prefixes based on API key.

Last 7 characters from API key are now used as prefix for keys in Redis.
Changed Redis connection error message.
Updated application configuration info.
Updated API authorization info.
Changed license from GPLv2 to AGPL.

Since web sites and services are never distributed in the traditional sense, the AGPL is the GPL of the web.
Updated docs.
Added require PHP extensions to composer list.
Added results caching to single category fetch.

Add: genKey() function in CacheInterface. It produces md5() hash from arbitrary params passed. This is then used as a hash key. The input for the key are actually the
SQL query input params.
Add: Cache ops to getSingle() in CategoriesModel.
Change: Default cache ttl increased to 5 minutes.