fixed file name formatter for large iterations
fixed file name formatter for large iterations

mrakitin/sirepo,mkeilman/sirepo,mrakitin/sirepo,mkeilman/sirepo,radiasoft/sirepo,mrakitin/sirepo,radiasoft/sirepo,radiasoft/sirepo,radiasoft/sirepo,mrakitin/sirepo,mkeilman/sirepo,mkeilman/sirepo,radiasoft/sirepo