Merge branch 'release/0.3.1'
Add logging to time patched source queries
Adds sharing ability to flat mapped producers also
Simplify the producer viz code. Don't try do anything clever, show every node in the graph even IdentityKeyedProducers
Add's test for failing user graph, where merge node was also a fork node.

Adds fix also
Minor variable name cleanup
Add some more info in debug output in test
In light of the not passing the maps around, the rest of this code gets much simplified too.
Merge pull request #417 from twitter/feature/fix_merge_planner_bug

Feature/fix merge planner bug
Merge branch 'develop' of github.com:twitter/summingbird into feature/shard-FM
Use the latest scalding's shard function
Merge pull request #416 from twitter/feature/shard-FM

Feature/shard fm
Adds also tail producer
Both args can be tail producer to the AlsoTailProducer
Fixup so tests pass
Use DummyImplicit
Some special casing so AlsoTailProducer survives intact through functionalization
Merge pull request #423 from twitter/feature/alsoTailProducerSupport

Feature/also tail producer support
Move code with no scalding deps over into a summingbird-batch-hadoop project
Few missing entries