[NaCl SDK] Bump version of visual studio addin that we ship 1568 -> 1573

native_client_sdk/src/build_tools/json/naclsdk_manifest2.json

 {
   "bundles": [
     {
       "archives": [
         {
           "checksum": {
             "sha1": "61bc0ab13c4ff1d3222446fb616f207b1617441f"
           },
           "host_os": "all",
           "size": 29619,
@@ skipping 11 matching lines @@
       "archives": [
         {
           "host_os": "win",
           "url": "https://storage.googleapis.com/nativeclient-mirror/nacl/nacl_sdk/sdk/${revision}/vs_addin.tgz"
         }
       ],
       "description": "Visual Studio Add-In for building and debugging NaCl applications",
       "name": "vs_addin",
       "recommended": "no",
       "repath": "vs_addin",
-      "revision": 1568,
+      "revision": 1573,
       "stability": "dev",
       "version": 0
     },
     {
       "archives": [
         {
           "checksum": {
             "sha1": "32c221b3f6bb58e160e3c1bd8a1e2330e3f411b4"
           },
           "host_os": "all",
@@ skipping 317 matching lines @@
       "name": "pepper_canary",
       "recommended": "no",
       "repath": "",
       "revision": 0,
       "stability": "canary",
       "version": 0
     }
   ],
   "manifest_version": 2
 }