Adjusted the comment in the wsgi.py file. We do not use mod_wsgi so it was pointless to mention this solely in the comment, now mentions Gunicorn
Removed some alerts stuff.

Alerts requires some more thinking. Little stubs such as the alerts view will probably be the same but lib/alerts.py requires a better design. This commit added some things but also reset a few.

Subscribtion reasons have been moved in to posts as this is a complete posts feature.

Also added ALERT_ITEMS_PER_PAGE to settings so that more can be shown compared to posts and comments.
Moved unit tests to inherit from base test cases.

Added BackendTestCase and FrontendTestCase to new file pjuu.lib.tests. All unittests in each sub-packages tests.py file now inherit from these.