Ensure Redis Configured to Send Keyspace Notifications

Previously there was a possibility that Session to WebSocket mapping was
leaked if keyspace notifications were not enabled in Redis.

To resolve this the RedisHttpSessionConfiguration now ensures that Redis
is configured to enable Keyspace notifications.

Fixes gh-76 gh-81
samples/web->samples/httpsession
Move Java Versions to gradle.properties
Ensure values of _s are encoded

Fixes gh-80
Add REST sample

Fixes gh-89
Start Documentation

Issue gh-41