Instead of using dojo.date.toRfc3339(jsDate) you could create your own function with a custom format string.

Something like the following would remove the colon and should be parsable by your java format.

function toRfc3339String(jsDate){
    return dojo.date.locale.format(jsDate,{selector: 'date', datePattern:'yyyy-MM-dd\'T\'hh:mm:ssZ'});
}