The Collection mixin adds support for executing a view, and passing
back the view results as an Array of the given ExtendedDocument instance.
It also supports will_paginate like pagination methods (paginate, paginated_each),
which will only fetch the given set of documents from CouchDB.
Examples:
db = CouchRest::Database.new(...)
articles = Article.on(db)
articles.all { ... }
articles.by_title { ... }
u = articles.get("someid")
u = articles.new(:title => "I like plankton")
u.save # saved on the correct database
