Replace deprecated electron-prebuilt with electron@2.0.18

- Updated package.json to use electron@2.0.18 instead of electron-prebuilt@1.4.3
- Modified lib/jibo-cli.js to reference 'electron' instead of 'electron-prebuilt'
- This fixes compatibility issues with the simulator on modern Linux systems
- electron-prebuilt was deprecated and renamed to electron in 2016

package.json

@@ -11,7 +11,6 @@
   "bin": {
     "jibo": "./bin/jibo.js"
   },
-  "peerDependencies": {},
   "dependencies": {
     "animation-utilities": "beta",
     "async": "0.9.0",
@@ -19,7 +18,7 @@
     "colors": "^1.1.2",
     "commander": "2.8.1",
     "compute-hamming": "^1.1.0",
-    "electron-prebuilt": "^1.4.3",
+    "electron": "^2.0.18",
     "ensureDir": "^1.0.6",
     "extract-zip": "^1.4.1",
     "find-root": "^1.0.0",