Added script to create DMG installers

installers/create-dmg.js

@@ -0,0 +1,19 @@
+const createDMG = require('electron-installer-dmg')
+const path = require('path')
+const package = require('../package.json');
+
+var opts = {
+  appPath: path.join(__dirname, '../release-builds/openflexure-ev-darwin-x64/openflexure-ev.app'),
+  name: package.productName,
+  icon: path.join(__dirname, '../icons/mac/icon.icns'),
+  out: path.join(__dirname, '../release-builds/installers', package.version)
+}
+
+createDMG(opts, function done (err) {
+  if (err) {
+    console.log(`Error creating dmg: ${err}`)
+  }
+  else {
+    console.log("Done")
+  }
+ })