LevelUP adapter: a work in progress.
Ignore the levelup test db.
Implmented Levelup.prototype.merge()

Now it's jsut the attachments implementation left to do.
Store attachments in a separate binary-encoded database.

Namespace all keys, so models can co-exist in a database.
Attachments aren't quite working yet, possibly because I have
misunderstood something about how batch operations work.
And the levelup adapter is now working.

Seems like it was a problem with the options I was passing to the db
creator.
Prepping for release.

Bumped the version number.
Updated the documentation to include LevelUP examples and to
de-couch-ify things that are now more general.
Merge pull request #8 from ceejbot/levelup

Support LevelUP with a new adapter