Doc: Generate documentation with Sphinx

HTML documentation should be built with sphinx. This enables easy
integration with Read The Docs [1]. It can also be generated manually by
running:

    make -C docs html

A man page can be generated by running:

    make -C docs man

[1]: http://yamllint.readthedocs.org/

yamllint/__init__.py

@@ -25,8 +25,8 @@ APP_NAME = 'yamllint'
 APP_VERSION = '0.4.0'
 APP_DESCRIPTION = 'A linter for YAML files.'
 
-__author__ = 'Adrien Vergé'
-__copyright__ = 'Copyright 2016, Adrien Vergé'
+__author__ = u'Adrien Vergé'
+__copyright__ = u'Copyright 2016, Adrien Vergé'
 __license__ = 'GPLv3'
 __version__ = APP_VERSION