Fixes query encoding to be like Quickbooks expects it. closes #6

Quickbooks [querying documentation](https://developer.intuit.com/docs/0025_quickbooksapi/0050_data_services/020_key_concepts/00300_query_operations) doesn't mention it explicitly, but it requires the query param to be encoded like form data.

So if your query had elements like ` ' " + = > < ] `, `URI.encode` would leave them as is, what would give as an error. 

`URI.encode_www_form_component` does the job correctly encoding the param as it should.

This fixed my issue #6.

Thanks! :beer: