remove mongodb bits from documentation

[Will Kahn-Greene]

The documentation in docs/ talks about installing and configuring mongodb. That should be removed.

M=d2eab) saturn ~/projects/mediagoblin/docs/source> grin -i mongodb
./codebase.rst:

85 : ORM for MongoDB we're using which will make it easier to define

151 : :models.py: holds the mongodb schemas---these are the data structures

./deploying.rst:

114 : Configure MongoDB

122 : First, install MongoDB. On a DEB-based system run

124 : sudo apt-get install mongodb 128 : yum install mongodb-server 130 : After installing MongoDB some preliminary database configuration may 133 : Ensure that MongoDB `journaling 134 : <​http://www.mongodb.org/display/DOCS/Journaling>`_ is enabled. Journaling 135 : is enabled by default in version 2.0 and later 64-bit MongoDB instances. 141 : Running MongoDB without journaling risks general data corruption 145 : MediaGoblin recommends enabling MongoDB's journaling feature by 149 : MongoDB can take a lot of space by default. If you're planning on