Update all dependencies.

* Switch to using kingpin for CLI interface as upstream Prometheus has moved
  that way too.

vendor/github.com/lib/pq/ssl_permissions.go

@@ -0,0 +1,20 @@
+// +build !windows
+
+package pq
+
+import "os"
+
+// sslKeyPermissions checks the permissions on user-supplied ssl key files.
+// The key file should have very little access.
+//
+// libpq does not check key file permissions on Windows.
+func sslKeyPermissions(sslkey string) error {
+	info, err := os.Stat(sslkey)
+	if err != nil {
+		return err
+	}
+	if info.Mode().Perm()&0077 != 0 {
+		return ErrSSLKeyHasWorldPermissions
+	}
+	return nil
+}