Where

Ok, How about this for a solution to the UUID issue #13. I changed the public API to be slightly:

Find one
```ruby
UserRepository.find(id)
```

Query
```ruby
UserRepository.where(email: 'matt@gmail.com')
```

This also fixes another issue. Before you had to call .to_i on the id when passing the id in from params for example. Now you don't:

```ruby
UserRepository.find(params[:user_id])
```