build(npm): upgrade to Gatsby v2

Breaking: requires Gatsby v2 to work

package.json

@@ -12,7 +12,9 @@
   },
   "keywords": [
     "gatsby",
-    "gatsby-plugin"
+    "gatsby-plugin",
+    "netlify",
+    "cache"
   ],
   "author": "Benedikt Rötsch <[email protected]>",
   "bugs": {
@@ -26,19 +28,22 @@
   "license": "MIT",
   "dependencies": {
     "babel-runtime": "^6.26.0",
-    "fs-extra": "^6.0.1"
+    "fs-extra": "^7.0.0"
   },
   "devDependencies": {
     "babel-cli": "^6.26.0",
-    "cross-env": "^5.0.5",
-    "eslint": "^4.19.1",
-    "eslint-config-prettier": "^2.9.0",
-    "eslint-config-standard": "^11.0.0",
-    "eslint-plugin-import": "^2.12.0",
-    "eslint-plugin-node": "^6.0.1",
-    "eslint-plugin-prettier": "^2.6.0",
-    "eslint-plugin-promise": "^3.8.0",
-    "eslint-plugin-standard": "^3.1.0",
-    "prettier": "^1.13.4"
+    "cross-env": "^5.2.0",
+    "eslint": "^5.4.0",
+    "eslint-config-prettier": "^3.0.1",
+    "eslint-config-standard": "^12.0.0",
+    "eslint-plugin-import": "^2.14.0",
+    "eslint-plugin-node": "^7.0.1",
+    "eslint-plugin-prettier": "^2.6.2",
+    "eslint-plugin-promise": "^4.0.0",
+    "eslint-plugin-standard": "^4.0.0",
+    "prettier": "^1.14.2"
+  },
+  "peerDependencies": {
+    "gatsby": "^2.0.0"
   }
 }