Revert "Make electron-rebuild a postinstall op"

This reverts commit 17b6d1b.

Author: martpie

package.json

@@ -20,7 +20,7 @@
     "dev": "webpack --config webpack.dev.js --colors --watch",
     "museeks": "./node_modules/.bin/electron .",
     "museeks:debug": "./node_modules/.bin/electron . --enable-logging --devtools",
-    "postinstall": "electron-rebuild -f",
+    "modules:rebuild": "electron-rebuild -f",
     "package:lmw": "build -lmw --ia32 --x64",
     "package:l": "build -l --ia32 --x64",
     "package:w": "build -w --ia32 --x64",