Make docs build with 0 errors

Comment out an unnecessary configuration file option. This makes Sphinx emit
zero warnings when building documentation.

Make the configuration file flake8 and pylint compliant.
Run setup_abrt task after upstream install

The setup_abrt will run only on RHEL7.

Also improve the setup_abrt docstring to provide information about its
current availability only on RHEL7.

Closes #49
Merge pull request #50 from elyezer/abrt-rhel7

Run setup_abrt task after upstream install
Add distro_info task

The distro_info task will inspect /etc/redhat-release in order to
discover the distro and version.
Update distro information to use distro_info task

Use distro_info instead of asking for OS_NAME and OS_VERSION environment
variables.
Merge pull request #54 from elyezer/distro-info

Add distro_info task
Merge pull request #51 from Ichimonji10/clean-build

Make docs build with 0 errors
Updated Docs to reflect new environ variables.

The environmental variable ``DISTRO`` is no longer valid. Instead,
please use ``OS_NAME`` and ``OS_VERSION``. For most tasks, if you don't
provide a value for ``OS_VERSION``, then tests which make use of this
variable will default to the value of ``7``.