Rewrite-specific routes should be configured when test case is described, not globally.
Use assert.ifError instead of comparing to null.
Stylistic tweaks and linting.
Remove unused 'express' require in test.
Add istanbul for code coverage.

`npm test --coverage` generates results, but basic `npm test` remains unsullied.
Add --print both to istanbul invocation.
Bump mocha to latest.
Merge branch 'not-constantinople' of git://github.com/zillow/combohandler