merged branch Seldaek/composer_alias (PR #3457)

Commits
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bafcaaf Removed version field
f9d9dc7 Add branch-alias for composer

Discussion
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Add branch-alias for composer

This should restore the 2.1-dev version (as an alias of dev-master) so that `2.*` or `2.1.*` constraints work again. I'll adjust packagist soon to also display those aliases.

composer.json

@@ -4,7 +4,6 @@
     "description": "Symfony Serializer Component",
     "keywords": [],
     "homepage": "http://symfony.com",
-    "version": "2.1.0",
     "license": "MIT",
     "authors": [
         {
@@ -22,5 +21,10 @@
     "autoload": {
         "psr-0": { "Symfony\\Component\\Serializer": "" }
     },
-    "target-dir": "Symfony/Component/Serializer"
+    "target-dir": "Symfony/Component/Serializer",
+    "extra": {
+        "branch-alias": {
+            "dev-master": "2.1-dev"
+        }
+    }
 }