Use babel 5 for karma tests

package.json

@@ -40,13 +40,15 @@
     "velocity-animate": "^1.2.3",
     "velocity-ui-pack": "^1.2.2"
   },
+  "//babelversion": [
+      "brief experiments with babel6 seems to show that it generates source ",
+      "maps which confuse chrome and make setting breakpoints tricky. So ",
+      "let's stick with v5 for now."
+  ],
   "devDependencies": {
     "babel": "^5.8.23",
-    "babel-core": "^6.7.4",
-    "babel-loader": "^6.2.4",
-    "babel-preset-es2015": "^6.6.0",
-    "babel-preset-react": "^6.5.0",
-    "babel-runtime": "^6.6.1",
+    "babel-core": "^5.8.38",
+    "babel-loader": "^5.4.0",
     "expect": "^1.16.0",
     "json-loader": "^0.5.3",
     "karma": "^0.13.22",