Updating dockerfile for release v1.3.0-rc1

docker/1.3/Dockerrun.aws/.ebextensions/01_files.config

@@ -0,0 +1,14 @@
+files:
+    "/etc/nginx/conf.d/proxy.conf":
+      mode: "000755"
+      owner: root
+      group: root
+      content: |
+        client_max_body_size 50M;
+    "/opt/elasticbeanstalk/hooks/appdeploy/post/init.sh":
+      mode: "000755"
+      owner: root
+      group: root
+      content: |
+        #!/usr/bin/env bash
+        gpasswd -a ec2-user docker 

docker/1.3/Dockerrun.aws/Dockerrun.aws.json

@@ -0,0 +1,13 @@
+{
+  "AWSEBDockerrunVersion": "1",
+  "Image": {
+    "Name": "mattermost/platform:1.3",
+    "Update": "true"
+  },
+  "Ports": [
+    {
+      "ContainerPort": "80"
+    }
+  ],
+  "Logging": "/var/log/"
+}