Refactor "Spam"-Method and GUI-Text to execute it

[Grauen]

Currently the api command "postattachToTangle" is mapped to a button which says "Start Spam". This could be greatly improved by

• using a useful text so people actually know what happens if they click the button
• add a timer users can configure, instead of just looping like this

        shouldSpam = true;
        var spamCount = 0;
        console.log("STARTED SPAMMING");
        var transfers = [{
            'address': '999999999999999999999999999999999999999999999999999999999999999999999999999999999',
            'value': 0,
            'message': 'DOMISWAYTOOFUCKINGCOOL',
            'tag': 'TOTALLY'
        }]
        async.doWhilst(function(callback) {
            iotajs.api.sendTransfer('999999999999999999999999999999999999999999999999999999999999999999999999999999999', 9, 18, transfers, function(e,s) {
                console.log(s);
                console.log("Spam Count: ", spamCount);
                spamCount += 1;
                callback(null);
            })
        }, function() {
            return shouldSpam === true;
        }, function() {
            console.log("STOPPED SPAMMING")
        })
    }```


Looks pretty nasty to me ;)