add csi-test to vendor

vendor/github.com/golang/mock/.gitignore

@@ -0,0 +1,17 @@
+# Object files and binaries from go.
+*.[568]
+
+# Library files.
+*.a
+
+# Any file prefixed by an underscore.
+*/_*
+
+# Vim temporary files.
+.*.swp
+
+# The mockgen binary.
+mockgen/mockgen
+
+# A binary produced by gotest.
+#gomock/[568]\.out