Add basic documentation of importing data into the CMS for development

doc/development.md

+# Running the CMS
+
+One can start the CMS by running `rake cms`. This will run the server on localhost
+port 8001.
+
+However, the server also needs data to work from.
+
+## Installing Mongodb
+
+Please see http://www.mongodb.org/downloads for more detailed instructions.
+
+### Ubuntu
+
+    sudo apt-get install mongodb
+
+### OSX
+
+    Use the MacPorts package `mongodb` or the Homebrew formula `mongodb`
+
+## Initializing Mongodb
+
+Check out the course data directories that you want to work with into the
+`GITHUB_REPO_ROOT` (by default, `../data`). Then run the following command:
+
+
+    rake django-admin[import,cms,dev,../data]
+
+Replace `../data` with your `GITHUB_REPO_ROOT` if it's not the default value.
+
+This will import all courses in your data directory into mongodb