added several validation functions and changed is_opt_field
added several validation functions and changed is_opt_field

sahana/vesuvius,sahana/vesuvius,bobrock/vesuvius,bobrock/vesuvius,ramdesh/vesuvius_installer,sahana/vesuvius,bobrock/vesuvius,sahana/vesuvius,sahana/vesuvius,bobrock/vesuvius,ramdesh/vesuvius_installer,ramdesh/vesuvius_installer,ramdesh/vesuvius_installer,bobrock/vesuvius,bobrock/vesuvius