Cache TTL should be a Duration instead of Time
Keep the interface of storehaus-redis in sync with storehaus-memcached
Define the WithPutTtl trait
Rename withTtl method to withPutTtl
Adding comments to docs about setting expiration for items
Merge branch 'develop' of https://github.com/twitter/storehaus into develop

Conflicts:
	storehaus-redis/src/main/scala/com/twitter/storehaus/redis/RedisLongStore.scala
	storehaus-redis/src/main/scala/com/twitter/storehaus/redis/RedisStringStore.scala
Merge pull request #100 from ximyu/develop

Cache TTL should be a Duration instead of Time