Add dryrun script and expand npmignore

Just housekeeping.
> This completely defeats the idea of, say, running tests on every module download to make sure they (still) work in your node version.

I've never been approached with that request and it still depends on the quality of the tests, so I'd be surprised if it was used as a general smoke test for applications. The integration tests in one's own module would be more dependable and telling should an issue arise. Also, my general impression from the [docs](https://www.npmjs.org/doc/misc/npm-scripts.html) is that scripts are intended for module authors to manage and dictate behavior during the client usage lifecycle. There's no implication there that the deliverable should include or export client-consumable test cases.

> And defeats anyone who wants to just run a service that reports the test status of modules on npm.

see travisci :smile: