bump dependencies

Author: jamestalmage

package.json

@@ -26,11 +26,11 @@
   ],
   "dependencies": {},
   "devDependencies": {
-    "ava": "^0.8.0",
+    "ava": "^0.14.0",
     "coveralls": "^2.11.6",
     "fake-module-system": "^0.3.0",
-    "nyc": "^5.0.0",
-    "xo": "^0.12.0"
+    "nyc": "^6.2.1",
+    "xo": "^0.13.0"
   },
   "xo": {
     "ignores": [