update logo (#111)

Author: shawnmssu

.github/terraform_logo.svg

@@ -5,7 +5,9 @@ Terraform Provider
 - [![Gitter chat](https://badges.gitter.im/hashicorp-terraform/Lobby.png)](https://gitter.im/hashicorp-terraform/Lobby)
 - Mailing list: [Google Groups](http://groups.google.com/group/terraform-tool)
 
-<img src="https://cdn.rawgit.com/hashicorp/terraform-website/master/content/source/assets/images/logo-hashicorp.svg" width="600px">
+<a href="https://terraform.io">
+    <img src=".github/terraform_logo.svg" width="600px">
+</a>
 
 Requirements
 ------------