Update properties in sendMock

[openam]

We should update the properties in the error to be something like errorData and errorCode.
https://github.com/sinet/lapin-mock/blob/master/lib/sendMock.js#L14-L15

I've seen tests that are too loosely written with like this:

it( 'should return `error` status', function () {
    sendMock.should.have.property( 'error' );
} );

By default sendMock will always have an error property. If the tests were written tighter and checked to make sure it was no longer a function it would be fine, or better yet it should assert the actual error message.