DOMAIN_MODULE_MAP should live in couch and not settings.py

couch doc will have id of `DOMAIN_MODULE_CONFIG` and will look like:

```javascript
{
   "_id": "DOMAIN_MODULE_CONFIG",
   "_rev": "2-b0463dc60ec88b81dea3d23618d24a18",
   "module_map": {
       "a5288-test": "a5288",
       "a5288-study": "a5288",
       "care-bihar": "bihar",
       "dca-malawi": "dca",
       "eagles-fahu": "dca",
       "mvp-potou": "mvp",
       "mvp-sauri": "mvp",
       "mvp-bonsaaso": "mvp",
       "mvp-ruhiira": "mvp",
       "mvp-mwandama": "mvp",
       "mvp-sada": "mvp",
       "psi-unicef": "psi"
   }
}
```