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I have reopened my bower.json, my line has been replaced by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