remove coins.json on init

ipc/shepherd-ipc.js

@@ -230,6 +230,7 @@ ipcMain.on('shepherd-command', (event, arg) => {
 StartMarketMaker = function(data) {
       //console.log(data.passphrase);
     try {
+      fs.unlink(BarterDEXDir+'/coins.json');
       // check if marketmaker instance is already running
       portscanner.checkPortStatus(7783, '127.0.0.1', function(error, status) {
         // Status is 'open' if currently in use or 'closed' if available