NumberedShardSpec

Each shard has a number, and there are a fixed number of shards that will
form a complete set.
Add missing license headers
Merge branch 'master' into num-shard-spec
More NumberedShardSpec serde tests
Merge branch 'master' into num-shard-spec

Conflicts:
	common/src/main/java/com/metamx/druid/partition/IntegerPartitionChunk.java
Fix test oopsie
Fix test oopsie
Merge pull request #225 from metamx/num-shard-spec

NumberedShardSpec