Switch to new vendor directory layout

Fixes #113

Signed-off-by: Marcos Lilljedahl <marcosnils@gmail.com>

vendor/github.com/docker/docker/pkg/system/path_unix.go

@@ -0,0 +1,8 @@
+// +build !windows
+
+package system
+
+// DefaultPathEnv is unix style list of directories to search for
+// executables. Each directory is separated from the next by a colon
+// ':' character .
+const DefaultPathEnv = "/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin"