I have edited my bower.json

"fontawesome": "~4.1.0",

by

"fontawesome": "https://github.com/FortAwesome/Font-Awesome.git#~4.2.0"

Then I did bower install fontawesome --save

It finally updated fontawesome

 

I have reopened my bower.json, my line has been replaced by

"fontawesome": "~4.2.0",

Hope it helped