Python 3: cast map() result to list

On Python 3, map() returns a generator, not a list. Cast explicitly the result
of map() to a list to get a list on Python 2 and Python 3.

The cast is useless in Python 2, but it doesn't hurt performances: it's just a
unit test.

Change-Id: I87486b7dbc42507a6fd7886748a2e09735b6fc5b
Python 3: Fix tests using temporary text files

Use mode "w" instead of the default mode "wb+" to get text file instead of
binary file on Python 3.

Change-Id: I2efe8d926309cfcd5ffe4ea963c11799773def73
Make bin/swift testable part 1

To make bin/swift importable for testing it needs to be renamed/moved.
The final idea is to move it to swiftclient/shell.py and add only a stub
in bin/swift to import swiftclient/shell.py.

However, doing this in a single step makes reviewing very hard, because
now there are > 1400 lines deleted from bin/swift and added to
swiftclient/shell.py - Gerrit doesn't detect the moved file.

For example: https://review.openstack.org/#/c/73710/2/

This patch first moves the code to swiftclient/shell.py and uses
setup.py/cfg to create the stub file in bin/swift. A follow up
(https://review.openstack.org/#/c/76489/) will then add the stub itself
in bin/swift (and remove the entry in setup.py).

The change to tox.ini is related to bug 1290562 and can be removed in
the future.

Change-Id: Id86392ccaf09e1d80a5d808fb49827d6d18c2588
Python 3: Replace iter.next() with six.next(iter)

Use six.next() to be Python 3 compatible.

Change-Id: Ia16148a759d368872787d5896a7b1dc42ffcdfb5
Replace dict.iteritems() with dict.items()

dict.iteritems() has been removed in Python 3. In Python 2, dict.items()
creates a temporary list, but Samuel Merritt wrote:

"The size of the data is small enough that we don't need to worry about the
memory consumption; it's all just HTTP headers."

Change-Id: Iac427b8bbd032e4a1efb2bdc84a3968217eb6ddf
Python 3: Add six dependency

Change-Id: I350eb089e02b4c33cf34c9fdb65289a2ad77f9c9
Merge "Python 3: Replace iter.next() with six.next(iter)"
Merge "Python 3: Fix tests using temporary text files"
Merge "Python 3: cast map() result to list"
Merge "Python 3: Add six dependency"