Fixes for a couple of issues I was having

I was able to fix a couple of issues I was having.

First is https://github.com/stevermeister/ngWig/issues/21 
To fix that, I added a condition, so that the css link is not inserted into iframe, if cssPath is not specified.

The second issue is that a client had to include ng-wig.css manually into his page. To fix that, I included the css into bower.json's main section.

Hope this helps and thank you for a wonderful editor! :)