[recipes.cfg] convert to JSON

Bug: 699379
Change-Id: I917b34b36e7e7d3b0ef4773a57c7905ec4eccb18
Reviewed-on: https://chromium-review.googlesource.com/458595
Reviewed-by: Daniel Jacques <dnj@chromium.org>
Commit-Queue: Robbie Iannucci <iannucci@chromium.org>

infra/config/recipes.cfg

@@ -1,8 +1,12 @@
-api_version: 1
-project_id: "depot_tools"
-deps {
-  project_id: "recipe_engine"
-  url: "https://chromium.googlesource.com/external/github.com/luci/recipes-py.git"
-  branch: "master"
-  revision: "3125a3b89e18dff89cf6d59f0a0486d832521bf1"
+{
+  "api_version": 1,
+  "project_id": "depot_tools",
+  "deps": [
+    {
+      "project_id": "recipe_engine",
+      "url": "https://chromium.googlesource.com/external/github.com/luci/recipes-py.git",
+      "branch": "master",
+      "revision": "3125a3b89e18dff89cf6d59f0a0486d832521bf1"
+    }
+  ]
 }