Switch packer to pull from master

cloudy_mozdef/packer/packer.json

@@ -33,7 +33,7 @@
         "sudo systemctl enable docker",
         "sudo mkdir -p /opt/mozdef/",
         "sudo git clone https://github.com/mozilla/MozDef /opt/mozdef",
-        "cd /opt/mozdef && sudo git checkout reinvent"
+        "cd /opt/mozdef && sudo git checkout master"
       ]}
  ]
 }