Pin dependency versions

package.json

@@ -43,16 +43,16 @@
   },
   "homepage": "https://github.com/lukechilds/node-browser-environment#readme",
   "dependencies": {
-    "jsdom": "^9.2.0"
+    "jsdom": "9.2.0"
   },
   "devDependencies": {
-    "ava": "^0.16.0",
-    "babel-cli": "^6.9.0",
-    "babel-plugin-add-module-exports": "^0.2.1",
-    "babel-preset-es2015": "^6.9.0",
-    "coveralls": "^2.11.9",
-    "eslint": "^3.2.2",
-    "eslint-config-lukechilds": "^1.9.0",
-    "nyc": "^7.1.0"
+    "ava": "0.15.2",
+    "babel-cli": "6.9.0",
+    "babel-plugin-add-module-exports": "0.2.1",
+    "babel-preset-es2015": "6.9.0",
+    "coveralls": "2.11.9",
+    "eslint": "3.2.2",
+    "eslint-config-lukechilds": "1.9.0",
+    "nyc": "7.1.0"
   }
 }