Fix legacy prebuilds electron 3.x macOS/Windows (#764)

* fix legacy electron 3x builds closes #760

* Add compatibility for Atom Electron 3.x builds

Author: the-j0k3r

CHANGELOG.md

@@ -1,3 +1,7 @@
+## 2.9.4 - PlatformIO
+
+* add compatibility for Atom Electron 3.x builds
+
 ## 2.9.3 - PlatformIO
 
 * Fix broken terminal

package.json

@@ -42,7 +42,7 @@
   },
   "dependencies": {
     "atom-space-pen-views": "^2.2.0",
-    "node-pty-prebuilt-multiarch": "^0.8.1",
+    "node-pty-prebuilt-multiarch": "0.9.0-beta21.legacy",
     "term.js": "https://github.com/jeremyramin/term.js/tarball/master",
     "underscore": "^1.8.3"
   },