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/golang.org/x/sys/unix/syscall_darwin.go b/vendor/golang.org/x/sys/unix/syscall_darwin.go
index 04042e4..a2e3688 100644
--- a/vendor/golang.org/x/sys/unix/syscall_darwin.go
+++ b/vendor/golang.org/x/sys/unix/syscall_darwin.go
@@ -416,6 +416,7 @@
 //sys	Chmod(path string, mode uint32) (err error)
 //sys	Chown(path string, uid int, gid int) (err error)
 //sys	Chroot(path string) (err error)
+//sys	ClockGettime(clockid int32, time *Timespec) (err error)
 //sys	Close(fd int) (err error)
 //sys	Dup(fd int) (nfd int, err error)
 //sys	Dup2(from int, to int) (err error)