makes cast_native cast floats with no leading digits.
Merge pull request #87 from wrshawn/float_fix

makes cast_native cast floats with no leading digits.
use method for CouchPotato

- returns a instance to a specific db
- can be used to work with multiple databases in one project
make database host configurable
update view if RestClient responds with HTTP 500
Added `sum` function so reduce function that use it work correctly.
Fixed: fetching different classes with the same view (think `Model.all` view definition that emits a key that's the same in the superclass and all its subclasses) is now possible.