chore(package): update @angular/forms to version 5.1.2

Closes #53

Author: greenkeeper[bot]

package.json

@@ -76,7 +76,7 @@
     "@angular/compiler": "^4.1.3",
     "@angular/compiler-cli": "^4.1.3",
     "@angular/core": "^4.1.3",
-    "@angular/forms": "^4.1.3",
+    "@angular/forms": "^5.1.2",
     "@angular/platform-browser": "^4.1.3",
     "@angular/platform-browser-dynamic": "^4.1.3",
     "@types/jasmine": "2.5.53",