Add unified-signature rule

https://github.com/typescript-eslint/typescript-eslint/blob/master/packages/eslint-plugin/docs/rules/unified-signatures.md

Author: sindresorhus

index.js

@@ -191,6 +191,7 @@ module.exports = {
 		'@typescript-eslint/restrict-plus-operands': 'error',
 		'@typescript-eslint/require-array-sort-compare': 'error',
 		'@typescript-eslint/type-annotation-spacing': 'error',
+		'@typescript-eslint/unified-signatures': 'error',
 
 		// TypeScript supports these features
 		'prefer-object-spread': 'error',

package.json

@@ -42,15 +42,15 @@
 		"simple"
 	],
 	"devDependencies": {
-		"@typescript-eslint/eslint-plugin": "^1.4.0",
-		"ava": "^1.2.0",
-		"eslint": "^5.14.1",
+		"@typescript-eslint/eslint-plugin": "^1.5.0",
+		"ava": "^1.3.1",
+		"eslint": "^5.15.3",
 		"temp-write": "^3.4.0",
-		"typescript": "^3.3.3"
+		"typescript": "^3.3.4000"
 	},
 	"peerDependencies": {
-		"@typescript-eslint/eslint-plugin": ">=1.4.0",
-		"eslint": ">=5.13.0",
-		"typescript": ">=3.3.3"
+		"@typescript-eslint/eslint-plugin": ">=1.5.0",
+		"eslint": ">=5.15.3",
+		"typescript": ">=3.3.4000"
 	}
 }