Fix iojs win

[springmeyer]

Makes adjustments to the tests to be able to pass with io.js + other refactoring that improves coverage and test consistency.

[Mithgol]

Somehow the changes made in TryGhost/node-sqlite3@cdd8d45 (they declare 2d72392 as the dependency) cannot prevent the message Module did not self-register on AppVeyor:

• platform=x86, line 624
• platform=x64, line 654

I guess something is not as simple as I've thought.

[springmeyer]

Those node-pre-gyp fixes only fixed the node-pre-gyp tests - they will have no impact elsewhere. But thanks for trying. So we must have some other problem in node-sqlite3?

[Mithgol]

Ah, I've just misunderstood the scope of #148.

If only the tests are fixed, then we should still wait for a fix either in the engine (nodejs/node#751) or in the building tool (nodejs/node-gyp#564); only then the generated modules won't cause that error message.

[springmeyer]

Right, or we find a way to call /path/to/iojs directly. But I don't currently have good ideas to do that.