common: Remove duplicate code

* Remove util/dictconfig.py as it's a duplicate of lib/dictconfig.py
common: Remove unused code in lib/singleton
pithos: Add Gevent Gunicorn Worker for Archipelago
pithos: Add glue code for Archipelago XSEG Object Pool and Gunicorn
pithos: Add monkey patch for making XSEG Request go green
pithos: Add configuration file for Gunicorn

Make workers delegate only one XSEG port pool
pithos: Add Archipelago Blocker and Mapper
pithos: Remove File - RADOS Blocker and Mapper

Add new constant for Archipelago configuration file in pithos API,
PITHOS_BACKEND_ARCHIPELAGO_CONF
pithos: Add support for recognizing Archipelago Volumes

Fix mapfile support the new snapshot naming

Introduce new IllegalOperationError exception

Add access control to Archipelago Volume hashmaps and blocks.
Raise an IllegalOperationError exception when trying to update an
Archipelago Volume
pithos: Introduce new register_object_map function

Register an object without providing any data. Cyclades can
use this function to register a newly created VM snapshot
pithos: pep8 fixes
pithos: Change relative import "base"

Relative import "base" should be "pithos.backends.base"
pithos: Remove unused import objpool
pithos: Do not put xseg request before map retrieval

During map_retr_archipelago, we should not put the xseg request which fetched
the map data, before actually retrieving them.

The ctypes "from_address" method, does not copy the data where the pointer
points. It simply creates a ctypes instance using the given memory. Ctypes
string_at method on the other hand, creates a new string object from the given
address, effectively copying the data out of the shared segment.

So, we should create the hashmap list from the request buffer before putting the
request and returning it (along with the associated buffer) to the segment.
pithos: Fix bug when catching IllegalExceptionError
pithos: Use synnefo.settings in backend/__init__.py
pithos: Move Xseg Pool initialization

Move Xseg Object Pool initialization to hashfiler module
pithos: Add snf-image support
pithos: Add default Archipelago config file

Add new constant ArchipelagoConfFile for the default Archipelago
config file. Set ArchipelagoConfFile after calling setupXsegPool
function.
pithos: Use new ArchipelagoConfFile constant

Remove BACKEND_ARCHIPELAGO_CONF and use the new ArchipelagoConfFile
introduced in WorkerGlue class.