use cross-env and update generated exe name

package.json

@@ -1,5 +1,5 @@
 {
-  "name": "loki-messenger-desktop",
+  "name": "session-messenger-desktop",
   "productName": "Session Messenger",
   "description": "Private messaging from your desktop",
   "repository": "https://github.com/loki-project/loki-messenger.git",
@@ -13,10 +13,10 @@
   "scripts": {
     "postinstall": "electron-builder install-app-deps && rimraf node_modules/dtrace-provider",
     "start": "electron .",
-    "start-multi": "NODE_APP_INSTANCE=1 electron .",
-    "start-multi2": "NODE_APP_INSTANCE=2 electron .",
-    "start-prod": "NODE_ENV=production NODE_APP_INSTANCE=devprod LOKI_DEV=1 electron .",
-    "start-prod-multi": "NODE_ENV=production NODE_APP_INSTANCE=devprod1 LOKI_DEV=1 electron .",
+    "start-multi": "cross-env NODE_APP_INSTANCE=1 electron .",
+    "start-multi2": "cross-env NODE_APP_INSTANCE=2 electron .",
+    "start-prod": "cross-env NODE_ENV=production NODE_APP_INSTANCE=devprod LOKI_DEV=1 electron .",
+    "start-prod-multi": "cross-env NODE_ENV=production NODE_APP_INSTANCE=devprod1 LOKI_DEV=1 electron .",
     "grunt": "grunt",
     "icon-gen": "electron-icon-maker --input=images/icon_1024.png --output=./build",
     "generate": "yarn icon-gen && yarn grunt",