Reorganize dist area to reduce -bin package size

Our -bin packages now exceed 200M. We need to do what we can to reduce their sizes in the future.

One of the biggest contributors to bloat in the bin package is the duplication of jars. While some of this is unavoidable (we will still need the connector-lib and connector-lib-proprietary directories, for instance), we can save maybe 100M simply by having only one copy of a jar for all jars used in explicit classpaths. The strategy of putting jars needed in a given classpath in a specific directory, for example, could be replaced by having jars reside in one place, and building class paths at compile time based on dynamic conditions. We may need an ant plugin for this, but I think it would be well worth it.