update Gopkg files

using master branch of gin, the code of tag 1.2 lost ShouldBind function

Gopkg.lock

   revision = "22d885f9ecc78bf4ee5d72b937e4bbcdc58e8cae"
 
 [[projects]]
+  branch = "master"
   name = "github.com/gin-gonic/gin"
   packages = [
     ".",
     "binding",
+    "json",
     "render"
   ]
-  revision = "d459835d2b077e44f7c9b453505ee29881d5d12d"
-  version = "v1.2"
+  revision = "bf7803815b0baa22ff7a10457932882dfbf09925"
 
 [[projects]]
   name = "github.com/golang/protobuf"
   ]
   revision = "ef8a98b0bbce4a65b5aa4c368430a80ddc533168"
 
+[[projects]]
+  name = "github.com/json-iterator/go"
+  packages = ["."]
+  revision = "ca39e5af3ece67bbcda3d0f4f56a8e24d9f2dad4"
+  version = "1.1.3"
+
 [[projects]]
   name = "github.com/magiconair/properties"
   packages = ["."]
   packages = ["."]
   revision = "00c29f56e2386353d58c599509e8dc3801b0d716"
 
+[[projects]]
+  name = "github.com/modern-go/concurrent"
+  packages = ["."]
+  revision = "bacd9c7ef1dd9b15be4a9909b8ac7a4e313eec94"
+  version = "1.0.3"
+
+[[projects]]
+  name = "github.com/modern-go/reflect2"
+  packages = ["."]
+  revision = "1df9eeb2bb81f327b96228865c5687bc2194af3f"
+  version = "1.0.0"
+
 [[projects]]
   name = "github.com/pelletier/go-toml"
   packages = ["."]
 [solve-meta]
   analyzer-name = "dep"
   analyzer-version = 1
-  inputs-digest = "8fe597b39b7ddfd166b23ba2d6c37c68c00acbcfe4aaab97b44ccfdda2394c0e"
+  inputs-digest = "189c9df81b72ddb72fa7c1b56c60dc172855975aa186420308ebe5ed25f83f76"
   solver-name = "gps-cdcl"
   solver-version = 1

Gopkg.toml

 
 [[constraint]]
   name = "github.com/gin-gonic/gin"
-  version = "1.2.0"
+  branch = "master"
 
 [prune]
   go-tests = true