[pgp] Move all Gajim PGP code into plugin

pgp/exceptions.py

@@ -0,0 +1,24 @@
+# Copyright (C) 2019 Philipp Hörist <philipp AT hoerist.com>
+#
+# This file is part of the PGP Gajim Plugin.
+#
+# PGP Gajim Plugin is free software; you can redistribute it and/or modify
+# it under the terms of the GNU General Public License as published
+# by the Free Software Foundation; version 3 only.
+#
+# PGP Gajim Plugin is distributed in the hope that it will be useful,
+# but WITHOUT ANY WARRANTY; without even the implied warranty of
+# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+# GNU General Public License for more details.
+#
+# You should have received a copy of the GNU General Public License
+# along with PGP Gajim Plugin. If not, see <http://www.gnu.org/licenses/>.
+
+class SignError(Exception):
+    pass
+
+class KeyMismatch(Exception):
+    pass
+
+class NoKeyIdFound(Exception):
+    pass