Accommodate 1.2.0-alpha as a potential version

Author: danielbachhuber

composer.json

@@ -27,7 +27,7 @@
     },
     "extra": {
         "branch-alias": {
-            "dev-master": "1.0.x-dev"
+            "dev-master": "1.x-dev"
         },
         "commands": [
             "scaffold package",