This modification introduce support of the new "desired node" field of download segment/object.
This can be used to request more nodes than the suggested minimum. It can be used to achieve better performance in exchange of using more bandwidth. (more parallel downloads).
Change-Id: Ia167d6979e6d70a597c85070a4ccd1c3a573e406
Most of our (~integration) tests based on testplanet runner.
However running testplanet for each test make the testing process slow.
It seems to be better to use real unit tests (without db dependency) when it's possible.
This patch makes small modification to make it possible to test orders.Service with real unit test.
As the existing unit test of `service.go` is isolated with `_test` package name, it's moved to an `_integration_test.go` file to make place for the unit test.
Change-Id: Ia69f26a34e2c48d230d8d36c2040dd02a60455a6
