Merge pull request #1689 from enzian/f_GoVendorExperiment

added excludes for vendored directories (since GO 1.5)

Go.gitignore

@@ -22,3 +22,7 @@ _testmain.go
 *.exe
 *.test
 *.prof
+
+# GO15VENDOREXPERIMENT flag specifics
+vendor/**
+!vendor/manifest