Add broadcasting to ShardManager
Refine API for BroadcastRequest and ShardManager

* new BroadcastRequest case class for broadcasts
* ShardManager attempts to infer key from Request object
* bump Akka to 2.3.4
Merge pull request #34 from paintcan/master

compute shard lookup in a Future
Version was bumped in README too soon.
Add note to readme about broadcast ask pattern
Resolved conflict with master.
Merge branch 'tysonjh-broadcast-head'
Bump version to 2.0.0

Add Tyson Hamilton to contributors.
Important Fix : Shardmanager was not replying to the right sender.
Updated readme.