Optimize out key.exists() call

Also try to retain the advantage that the error message returned when
a 404 is encountered still avoids the annoying gevent-instigated stack
trace.  This is done by converting exceptions into return values
rather than raising them to the top of the greenlet.
Untabify
Test compatability with newer boto

New Boto versions require a 'port' argument be supplied to
get_http_connection.
Updating storage layout to support alternative storage systems.
factoring parser definition to it's own function to make things a little easier to follow.
Moved arg validation in cmd.py to it's own function.
Initial pass over operator (WIP)
Initial pass over worker (WIP)
Centralized tarfile extraction in a static method on TarPartition.
caching store_name to avoid repeated calls to re.match.
Second pass over worker.
Initial pass over deleter.
Second pass over deleter
Added super() call to init method of WABS _Deleter subclass.
Updated WABS blobstore module, fixed errors in operator related to blobstore module.
Factored out chunks of S3 and WABS worker classes to common base class.
Added tests for WABS features.
Correcting return value of uri_put_file
Reducing read byte size to 1024.
Correcting references to worker module classes.