Update messages.yml

Italian translation provided.
Minor english typo corrected.
NOTE : 
Translation of : key admin_pw_required2
English and french text do not match.
English sentence does not make much sense as the french one does. Please clarify what the keys does so I will provide the ammended translation if required. In this italian translation I took for good the french one.
Please advice If changes is required.
Merge pull request #76 from bitnikrbt/patch-1

Update messages.yml - Italian translation