Refactor tests regarding required attributes

Some tests regarding the _required_attribute(s) functions in the wsgi
module seemed to be somewhat confusing, so I refactored them trying to
increase readability.

Change-Id: Id9aedcb05063cf0d618399847f6afe73c800aa93
Cleanup openstack-common.conf and sync from olso

An upcoming change[1] in oslo's update.py adds new warnings for
style issues in the config. To compensate this commit:

 - orders the modules alphabetically
 - uses the script directive for scripts

Sync with oslo-incubator caed79d

This syncs Keystone with oslo-incubator commit hash
caed79d8239679cb74476bb0d9e5011b4fcc39da.

In keystone:

$ rm -r keystone/openstack/common

In oslo-incubator:

$ python update.py ../keystone

Commits
-------

1173e46 Remove ValueError when accessing sys.modules
17c4e21 Fix docstring indentation in systemd
90ae24b Remove redundant default=None for config options
6c7407b fileutils: port to Python 3
18f2bc1 Enforce unicode json output for jsonutils.load[s]()
af36c2a Fix logging setup for Python 3.4
5ae792b Document config generator variables
ea9ead8 Allow file exclusion in config generator
cdcc19c Mask passwords that are included in commands
9e5a393 jsonutils.load() accepts file pointer, not string
a6b2aec On Python <= 2.6, use simplejson if available
fe3389e Improve help strings
8a0f567 Remove str() from LOG.* and exceptions
f3f14c9 Fixed several typos
0f495ee Emit a log statement when releasing internal lock
9912e5d Add API for creating translation functions

1. https://review.openstack.org/76901

Change-Id: I89de9ae9e3c574095967a2a67e842a90b5527ffa
Merge "Cleanup openstack-common.conf and sync from olso"
Merge "Refactor tests regarding required attributes"