Updates branch aliases

- dev-master => 1.7.x-dev
- dev-develop => 1.8.x-dev

Author: weierophinney

composer.json

@@ -18,8 +18,8 @@
   },
   "extra": {
     "branch-alias": {
-      "dev-master": "1.6-dev",
-      "dev-develop": "1.7-dev"
+      "dev-master": "1.7.x-dev",
+      "dev-develop": "1.8.x-dev"
     }
   },
   "require": {