Send reload message even for zero or undefined files

I have a setup where I don't know which files are changed but still want to trigger a reload. LiveReload.js supports this and will skip the reload filter and just reloads the full page. 

Now I modified tiny-lr to support this also: tiny-lr already created an empty `files` parameter but then the reload()-loop would do nothing so I added an if-clause. I hope that's ok.

I ran `npm test` before/after and they gave same result (= 4 pending test, I'm on node 0.10.1 on Vista 64)