Fixes for reported installation issues

Aaron;
This handles issues reported by Amit Indap on the mailing list:

- Now requires only IPython 0.13.2 instead of the development version.
- Provide a better error message for missing configuration files, pointing users at possibility of missing data files.
-  Only require configured data when doing loading to allow other functionality to work without data files. This opens up the possibility of having a "lite" gemini install that queries an existing database without needing all the associated files for creating new databases. It moves the configuration loading to run time instead of globally at import time.