Try to fix artifact download, + Diagnostics

Author: Piotr Puszkiewicz

.travis.yml

@@ -53,4 +53,7 @@ deploy:
   skip_cleanup: true
   on:
     repo: OmniSharp/omnisharp-vscode
-    tags: true
+    tags: true
+  overwrite: true
+
+after_deploy: "find . -type f -name '*.vsix'"