Extracting the DateTime tests and clarifying input params

Also moved the connection tests, in preparation for a more detailed API
spec.
Fixing API delegation tests and removing 'models' path
Add an integration test for filtering orders by date

This fixes an issue with recent changes to the API that broke the RFC
2822 DateTime encoding on URL parameters.

It also provides a new structure for running integration tests using VCR
and WebMock, and removes the FakeWeb library.
Set default environment vars to run recorded tests without config

Also fixes the 1.8.7 killing syntax that was exploding Travis CI.
Merge pull request #45 from maetl/fix-datetime-with-orders

Fix URL encoding of date-time parameters