View source for Bedrock/Get dev server usable

{{bedrock-feature
|bedrock-priority=P1
|bedrock-feature=Get development server usable
|bedrock-stage=Development
|bedrock-target=2011/12/15
|bedrock-notes=On course
}}
bedrock needs a dev server. We have this working at www-dev.allizom.org with the /b/ prefix: if the URL has that prefix, it is passed to bedrock.

This feature will track getting the dev server usable and working the way we except. There's still a few things here and there that are broken, so this isn't complete yet.

== DEV = True ==

The dev server needs the config value DEV set to True. The locale middleware uses this to detect activated locales; if DEV is False than it only allows locales specified in a hardcoded list in the settings. If it's True than it allows any locales available on the filesystem to be served.

I put DEV=True into the base settings to get the dev site working for now, but the obviously should not be the default. We need to remove this once this bug is completed:

https://bugzilla.mozilla.org/show_bug.cgi?id=708042