Added support for hit external services in a transparent way for the webapp.

I'm adding only support for hit 1 external server using the plugin `grunt-connect-proxy` which is based on `http-proxy` node module (full feature reverse proxy for node).

For more documentation please check:
0 - https://github.com/dendril/generator-tamagotchi/tree/feature/reverse-proxy#reverse-proxy-support-optional
1 - `npm info http-proxy`
2 - `npm info grunt-connect-proxy`

There are more features to integrate, but I guess it's a good start for automate reverse proxy configuration.

What do you think?