Add wrapper for commit-tree.
Add test for ConfigDict.iteritems.
Reimplement iteritems.
Add ConfigDict.itersections.
Update some copyright headers.
Move refs handling to a separate file.
Move read_info_refs from dulwich.client to dulwich.refs.
Move write_info_refs to dulwich.refs.
Support Swift Object Store as Git bare repository

This commit provides the minimal requirements to
use OpenStack Swift as backend for Dulwich.
The Swift Git repository only use pack and index
files to store objects and references are managed
through the info/refs file.
Remove monkey patching from that library

Monkey patching must by done in the
program entry point.
Fix wrong file name in header
Fix hasattr usage by using getattr instead
Fix typo
Fix docstrings

Fix first sentence on one line.
Remove useless space char.
Remove overriding of setUp() or tearDown() as useless
Replace assert by assertTrue
Create load_conf function to read config file

Avoiding trying to read configuration from a
relative path. Instead use an environment variable
or directly pass the configuration file path to
the SwiftRepo class.
Split eventlet code from swift.py

The eventlet code from swift_eventlet.py
will only be used if eventlet can be
imported. This fix remove the mandatory
need to have eventlet installed to run
the swift backend.
Hook up the standard ObjectStore tests to test_swift.py
Add functional tests for testing from a running Swift