Civicrm should check for a false return value on calling setlocale()

When civicrm calls setlocale() in Variables.php, it does not check for a return value of false. This means that either the php install does not have gettext installed or none of the locales are available and should cause an error to warn the user.

I have attached a patch against 3.0.3 to add a check for setlocale() returning false and throw a fatal error. (This is actually my first time submitting a patch, so hopefully I got the format right

Jordan