chore(package): update lerna to version 3.1.1

Closes #4

Author: greenkeeper[bot]

package.json

@@ -12,7 +12,7 @@
 	"devDependencies": {
 		"coveralls": "^3.0.0",
 		"istanbul": "^0.4.5",
-		"lerna": "^2.2.0",
+		"lerna": "^3.1.1",
 		"tslint": "^5.7.0",
 		"typescript": "^2.5.2"
 	}