add prune and remove unused packages

vendor/github.com/hashicorp/golang-lru/README.md

@@ -1,25 +0,0 @@
-golang-lru
-==========
-
-This provides the `lru` package which implements a fixed-size
-thread safe LRU cache. It is based on the cache in Groupcache.
-
-Documentation
-=============
-
-Full docs are available on [Godoc](http://godoc.org/github.com/hashicorp/golang-lru)
-
-Example
-=======
-
-Using the LRU is very simple:
-
-```go
-l, _ := New(128)
-for i := 0; i < 256; i++ {
-    l.Add(i, nil)
-}
-if l.Len() != 128 {
-    panic(fmt.Sprintf("bad len: %v", l.Len()))
-}
-```