Remove buildout

[cmc333333]

• Removes buildout in favor of requirements.txt
• Removes the src directory (as it's not particularly useful)
• Removes the extra buildout folder (which contained settings and urls only used w/ buildout). Its contents moved up a directory
• Allow settings to be overridden via local_settings.py
• Use a random secure key when one isn't specified

[m3brown]

Fixes the tests, and it works fine in our environment.

[m3brown]

Thanks a bunch, @cmc333333