clean up files

moved obsolete js files for board, post, topic to extras/
changed name of epochTest to testLevelDb
modularize board importer to  supply a boardStream

new module epochBoardStream returns a stream of boardObjects
that will be used in the importer
add epochThreadStream (similar to epochBoardStream)

creates a stream of threadObjects to import to core
skeleton of epochImporter
add epochPostStream (similar to other epochStreams)

used to submit posts to core

special processing done for posterTime (multiply by 1000 to get ms from
seconds)