Changed Configurable class

It makes more sense to assign real attributes once
instead of searching for proper value every time attribute is requested
If given attribute has a setter then it will be used
Don't use unmarshallable objects in stack's info()
s/(all|windows)/clients/g in the tests
send a synthetic ConfigureNotify event when position change

see 4.2.3. http://tronche.com/gui/x/icccm/sec-4.html

Closes #382
Make tests run on git version

Adding the __init__.py file to the tests directory causes nose to use
the code in the git directory, rather than the globally installed
version.  Additionally, changes to loading configuration files and
utility scripts allows for `nosetests` to be run from the root
directory.
Add qtile.egg-info to gitignore
Report support for _NET_WM_STRUT*

We have logic for respecting these, although we don't report support for it.

Closes #385
Prevent various crashes in qsh
Remove odd 'if self:' pattern.
Allow a default prompt in the prompt widget

Closes #386
Option to invert mouse wheel commands for groupbox

The option allows mouse-wheel up and down to invert next/prev group
selection.

Closes #381
Fix a test

Due to 3474efca6496e8ff762811b4f35bb4b00b58365b this no longer raises an
exception. We should probably do something here (i.e. report command not found
or whatever), but it definitely shouldn't crash qsh.
Fix test

Looks like this was an accidental change in
9bab48c8debca6ac8371062e206c89e21514b112.
Remove all references to _abort

This is unused (it is not set anywhere any more) so we can delete it.
fix keyboardlayoutwidget
improved _Call.when() method

Improved when() method for floating window
Rearrange logic a bit
Changelog for 0.7++
Only have a version number in one place
Update install instructions

We don't need a source version of libxcb.
We can do better than forcing people to define a custom xsession.