Fix filter name `failure` => `failed`
Fix CouchDB permissions handler
Roll CouchDB back to 1.6.1

- BigCouch additions don't make sense for single node
- "Fauxton" 2.0 web UI is nice, but not ready for primetime
Fix compilation errors in older CouchDB

- `_BSD_SOURCE` => `_DEFAULT_SOURCE` in newer `gcc`
- fix missing `THANKS` file