change from glyphicons images to glyphicons fonts

I try to fix the problem I mention in https://github.com/yeoman/generator-angular/pull/339#issuecomment-25715731 

I use the same method as with the old glyphicons.pngs, so a copy of these files is in the generator. (I think this could improved)
I also has to change the fonts path from /styles/fonts to /fonts. Otherwise the css files needs to updated in build. I don't know, if this is possible with one grunttask