Andjust the generation of Kernel download url

A small error but a big problem. This script generated an incorrect kernel download url : ...mainline/v3.15.8-utopi/.... instead of mainline/v3.15.8-utopic/... (the difference is a "c" character). I make a small change and now the script works again. Thanks for this script, It is very useful...
Merge pull request #5 from AlessioPaternoster/patch-1

Andjust the generation of Kernel download url