[FLINK-1110] Add collection-based execution mode to flink APIs

This modes executes programs straightforwardly as collections, with minimal resource footprint and virtually no latency (such as starting threads, RPC services, actor systems, ...)
You can use the `LocalCollectorOutputFormat` as a workaround.

We should start adding such "distributed-to-local" operations to the API in the next version. The runtime is adding functionality for that.
With the blob-manager in place, we should be able to do this nicely and robustly.