Deep update of XO and its dependencies

Fixes compatibility issues with Atom, see <sindresorhus/atom-linter-xo#74 (comment)>.

Author: novemberborn

package-lock.json

@@ -197,7 +197,7 @@
 		"temp-write": "^3.1.0",
 		"touch": "^1.0.0",
 		"typescript": "^2.2.2",
-		"xo": "^0.18.0",
+		"xo": "^0.18.2",
 		"zen-observable": "^0.5.1"
 	},
 	"typings": "types/generated.d.ts",