Make it possible to log to stderr always

This is useful for node-tap, which hides stdout
Move the DB handling out of github-watcher, into reader

This makes it a lot easier to test github-watcher :P
Add a link-parser to parse the github Link header

We need this for pagination
Make github-watcher fetch more pages of repos.

We do this parsing the Link header, and keep fetching so long as we have a "next" link. We emit an end event at the end as well (mainly used in the test).

The test, for now, is live, which means it is a bit slow, hence the increased timeout for `npm test`