Check in the vendor directory

Travis seems to be having issues pulling deps, so we'll have to check in
the vendor directory and prevent the makefile from trying to regenerate
it normally.

vendor/github.com/modern-go/concurrent/go_above_19.go

@@ -0,0 +1,15 @@
+//+build go1.9
+
+package concurrent
+
+import "sync"
+
+// Map is a wrapper for sync.Map introduced in go1.9
+type Map struct {
+	sync.Map
+}
+
+// NewMap creates a thread safe Map
+func NewMap() *Map {
+	return &Map{}
+}