Change tox.ini style with multi-line settings

Prefer to indent to a consistent width (four spaces) and always
breaking the line after the '=' sign for multi-line settings.
Add pep8 and pyflakes checking and omission criteria

These settings are the ones used so far to vet WAL-E by me.  It seems
to add an inconsequential amount of run time to the test suite, and
will hopefully help contributors submit patches less laborious for
those who maintain this once-arcane and unwritten standard.
Add a development guide to the README

Mostly covers usage of tox and testing.
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.