Added skeleton for 'dump' command.

Moved 'api.py' out of 'load' into 'common' package, added 'log' module
to 'common' package. Modularized and cleaned up things a bit.
Made api.put_mapping more generic.
Working 'esdump'

Tool for dumping data out of ES. Verified piping 'esdump' into 'esload'
to copy and index.