Increase accuracy in deduping from distributed systems

Increase accuracy in deduping from distributed systems by adding incr in Redis.

Redis fix

Merge pull request #3 from catmullet/fix-redis-err

Update redisonestore.go

Added bool return for AddKey and HasKey

Adding based on suggestion from jlnostr
AddKey now returns ok and error
HasKey now returns exists and error

Initial release

Merge pull request #1 from catmullet/add-license-1

Create LICENSE