README tweaks
Clean up some docstrings.
Added Douglas Fraser to AUTHORS
Added Mike Cornwell to AUTHORS
For dropdown fields in the forms builder app, use the placeholder text to provide an empty first choice.
Updated to Chosen 0.9.12

I upgraded Chosen to 0.9.12 because the old version (0.9.5) was breaking
with newer versions of jQuery that don't include the browser property.
I chose to add a version suffix to the chosen JS filename in order to
bust the cache.  I didn't upgrade to the newest version of Chosen
(1.1.0 at the time of this commit) because it doesn't support the dark
styles that is used for the chosen select in the header.
Add a custom banner to Mezzanine's runserver command, showing a logo and various software versions.
Handle new management command loading order in Django 1.7, so we can override runserver.
Make the setuptools test runner part of the mezzanine package so that we can call it from other packages (such as cartridge). Also make its local_settings module more dynamic.
Remove working directory hack from bundled manage.py - conflicts with Django runserver's auto-reloader when run from outside of project root.
Updated development instructions for setting up Mezzanine when contributing.
Update to latest patch versions of Django in travis config.
Fix travis config.
Better explansion example in dev setup docs.
Merge
Prep repo for translated docs.
New sites in README.
A test for the login_required property has been added.
A more complete test for the login_required property.
Empty line added.