couchdaemon: API cleanup

- added ConfigSection for retrieving whole sections
- added functions for level-based logging
- errors are propagated through the API
- the functions no longer hang when Init hasn’t been called
add .gitignore
couchdb: rework feeds implementation

- stateful iterator API modeled after database/sql.Rows
- added support for non-continuous _changes feeds
- added support for revisions and include_docs for _changes feeds
- improved documentation
- get rid of simplejson dependency