some improvements into the localization

this pull request includes:
- added some missing i18n strings
- a small css fix in the master.pt, the right column was missing the col-md-3 class
- improved the italian translation
- now the populate script will honor the default language of the portal. So, if the admin has already set the language before the populate script runs, the generated contents will be translated (notably the home page and the about page). I've run all the tests, and everything is still passing.