add cli command to show post details

suchwow/app.py

@@ -119,5 +119,14 @@ def remove_admin(username):
     else:
         print("That moderator doesn't exist")
 
+@app.cli.command("show")
+@click.argument("post_id")
+def post_id(post_id):
+    p = Post.filter(id=post_id).first()
+    if p:
+        print(p.show())
+    else:
+        print("That post doesn't exist")
+
 if __name__ == "__main__":
     app.run()