Support JSON in --extra-vars.

If --extra-vars starts with either a '{' or a '[', it will be assumed
we are dealing with JSON and parse the data as such.

bin/ansible-playbook

@@ -98,7 +98,10 @@ def main(args):
         if options.sudo_user or options.ask_sudo_pass:
             options.sudo = True
         options.sudo_user = options.sudo_user or C.DEFAULT_SUDO_USER
-    extra_vars = utils.parse_kv(options.extra_vars)
+    if options.extra_vars[0] in '[{':
+        extra_vars = utils.json_loads(options.extra_vars)
+    else:
+        extra_vars = utils.parse_kv(options.extra_vars)
     only_tags = options.tags.split(",")
 
     for playbook in args: