Bring in some of the Config changes from scalding into Summingbird, as a result killing off most of its own configuration code around hadoop properties.

• Removing internal config setup from scalding platform: https://github.com/twitter/summingbird/pull/629
• Remove store that no one seems to use and has no tests: https://github.com/twitter/summingbird/pull/630
• Ianoc/optimization changes: https://github.com/twitter/summingbird/pull/628
• Fixes tests: https://github.com/twitter/summingbird/pull/626
• resilient to all stores being complete: https://github.com/twitter/summingbird/pull/627
• Resilient to a store being ahead: https://github.com/twitter/summingbird/pull/625
• move to scala test: https://github.com/twitter/summingbird/pull/621
• Killing off Summingbird Java: https://github.com/twitter/summingbird/pull/624
• Kill summingbird spark: https://github.com/twitter/summingbird/pull/622
• Bumping sbt versions: https://github.com/twitter/summingbird/pull/623
• Fixed erroneous comment in ClientStore's merge description: https://github.com/twitter/summingbird/pull/620