PR 37 - blocking certain routes, unit tests

For https://github.com/bithavoc/express-winston/issues/37

- exposing an ignoredRoutes array, similar to how some other whitelists/blacklists are handled
- refactored unit tests to be somewhat more DRY, added unit test for 0.1.x to test ignoredRoutes, not sure what's different between 0.1.x and 0.2.x
- forgot to update README.md - if this actually has a chance of getting merged, I can update the documentation for ignoredRoutes