Fixed composer.json. Single quotes does not validate.

composer.json

@@ -3,17 +3,17 @@
     "type": "library",
     "description": "Doctrine2 behavioral extensions",
     "keywords": [
-        'behaviors',
-        'doctrine2',
-        'extensions',
-        'gedmo',
-        'sluggable',
-        'loggable',
-        'translatable',
-        'tree',
-        'nestedset',
-        'sortable',
-        'timestampable'
+        "behaviors",
+        "doctrine2",
+        "extensions",
+        "gedmo",
+        "sluggable",
+        "loggable",
+        "translatable",
+        "tree",
+        "nestedset",
+        "sortable",
+        "timestampable"
     ],
     "homepage": "http://gediminasm.org/",
     "license": "MIT",