init_log before start importing stuff

This fix stuff trying to log, before Qtile is instantiated
We should look for a better way to make this
add logging on widget imports

now the import errors stop being silent and displays an error when a
widget cannot be imported because it can't meet some dependency
remove timeout_add debug logs, it makes more noise than help
set default logging level to WARNING
add importlib as a dependency for python <= 2.6 and 3.0
fix widgets safe_import on python 3.2
add python 2.6 importlib dependency to the install docs
Add lazy functions and special keys documentation

Closes #512
update arch docs
add startup_once hook, which is called exactly once
Update gmail_checker.py

row_data is byte string. It doesn't have decode. Tested on python3
fix arch docs, qtile-git and qtile-python3-git were swapped

Closes #515
Put overvview first

The overview section is listed second in the config section. In every other
section overview is first--becaue overviews should be first.

Closes #516
update for cairocffi on pypi

Closes #517
update debian packaging for cairocffi release
fix the startup(_once) hook names

We should really abstract this and make it a little DRY-er so that I don't
screw this up again :)
Add documentation for autostart
Merge branch 'develop' of github.com:FrostyX/qtile into develop