VOL-1497 : Add more control to kv/memory access

- Added kv locking mechanism (etcd only)
- (watch) control path access whenever possible
- (watch) use a transaction for updates and merge with memory
- cleaned up vendoring
- misc changes to fix exceptions found along the way

Amendments:

- Copyright header got removed in auto-generated file
- Changed default locking to false for KV list operation
- Updated backend api to allow the passing of locking parameter

Change-Id: Ie1a55d3ca8b9d92ae71a85ce42bb22fcf1419e2c
diff --git a/vendor/github.com/gregjones/httpcache/httpcache.go b/vendor/github.com/gregjones/httpcache/httpcache.go
index f6a2ec4..b41a63d 100644
--- a/vendor/github.com/gregjones/httpcache/httpcache.go
+++ b/vendor/github.com/gregjones/httpcache/httpcache.go
@@ -416,14 +416,14 @@
 func getEndToEndHeaders(respHeaders http.Header) []string {
 	// These headers are always hop-by-hop
 	hopByHopHeaders := map[string]struct{}{
-		"Connection":          struct{}{},
-		"Keep-Alive":          struct{}{},
-		"Proxy-Authenticate":  struct{}{},
-		"Proxy-Authorization": struct{}{},
-		"Te":                struct{}{},
-		"Trailers":          struct{}{},
-		"Transfer-Encoding": struct{}{},
-		"Upgrade":           struct{}{},
+		"Connection":          {},
+		"Keep-Alive":          {},
+		"Proxy-Authenticate":  {},
+		"Proxy-Authorization": {},
+		"Te":                  {},
+		"Trailers":            {},
+		"Transfer-Encoding":   {},
+		"Upgrade":             {},
 	}
 
 	for _, extra := range strings.Split(respHeaders.Get("connection"), ",") {
@@ -433,7 +433,7 @@
 		}
 	}
 	endToEndHeaders := []string{}
-	for respHeader, _ := range respHeaders {
+	for respHeader := range respHeaders {
 		if _, ok := hopByHopHeaders[respHeader]; !ok {
 			endToEndHeaders = append(endToEndHeaders, respHeader)
 		}