update vendored dependencies

Gopkg.lock

@@ -2,16 +2,16 @@
 
 
 [[projects]]
-  branch = "master"
   name = "github.com/golang/protobuf"
   packages = ["proto"]
   revision = "925541529c1fa6821df4e44ce2723319eb2be768"
+  version = "v1.0.0"
 
 [[projects]]
-  branch = "master"
   name = "github.com/google/go-github"
   packages = ["github"]
   revision = "e48060a28fac52d0f1cb758bc8b87c07bac4a87d"
+  version = "v15.0.0"
 
 [[projects]]
   branch = "master"
@@ -23,7 +23,7 @@
   branch = "master"
   name = "golang.org/x/net"
   packages = ["context","context/ctxhttp"]
-  revision = "0ed95abb35c445290478a5348a7b38bb154135fd"
+  revision = "2fb46b16b8dda405028c50f7c7f0f9dd1fa6bfb1"
 
 [[projects]]
   branch = "master"