Add keymap downloading

Closes #199

package.json

@@ -12,6 +12,7 @@
     "@ngrx/store-log-monitor": "3.0.2",
     "@types/core-js": "0.9.35",
     "@types/electron": "^1.4.32",
+    "@types/file-saver": "0.0.0",
     "@types/jquery": "^2.0.40",
     "@types/node": "^7.0.5",
     "@types/usb": "^1.1.2",
@@ -47,8 +48,10 @@
     "@ngrx/store": "2.2.1",
     "bootstrap": "^3.3.7",
     "browser-stdout": "^1.3.0",
+    "buffer": "^5.0.3",
     "core-js": "2.4.1",
     "dragula": "^3.7.2",
+    "filesaver.js": "^0.2.0",
     "font-awesome": "^4.6.3",
     "jquery": "3.1.1",
     "json-loader": "^0.5.4",