Querying improvements

Minimal update (with tests) to provide ActiveRecord-like convenience methods, such as:
```ruby
Resource.where(:field=>"value").first_or_create
Resource.where(:field=>"value").first_or_initialize
Resource.where(:field=>"value").first_or_create :another_field=>"another_value"
Resource.where(:field=>"value").first_or_initialize :another_field=>"another_value"
```
Please feel free to comment, question, or suggest improvements.