VOL-1867 move simulated olt from voltha-go to voltha-simolt-adapter

Sourced from voltha-go commit 251a11c0ffe60512318a644cd6ce0dc4e12f4018

Change-Id: I8e7ee4da1fed739b3c461917301d2729a79307f5
diff --git a/vendor/github.com/hashicorp/go-immutable-radix/.travis.yml b/vendor/github.com/hashicorp/go-immutable-radix/.travis.yml
new file mode 100644
index 0000000..1a0bbea
--- /dev/null
+++ b/vendor/github.com/hashicorp/go-immutable-radix/.travis.yml
@@ -0,0 +1,3 @@
+language: go
+go:
+  - tip