Add pushstate support, rediscloud support, and tests

Hope I'm not stepping on anyone's toes; I decided to use `mean-seo` for one of my own projects and I had some fairly specific needs. Firstly, I needed HTML5 pushstate support, as detailed in #6, and then I also needed the `redis` cacheClient to support `rediscloud`.

I ended up adding an additional `cacheClient` option (`rediscloud`), and also coercing the SEO function in `lib/mean-seo.js` to also play nicely with HTML5 pushstate URLs. I also added a few basic tests, and a `travis-ci` config file. (here's a [successful build](https://travis-ci.org/tvararu/mean-seo/builds/31514960))

This shouldn't break the existing API in any way, but should add functionality. Let me know if there is anything that you don't think is proper and I can fix it and submit another PR.

This closes #6 and #5.