plugin XEP-0384: better bundle handling + misc improvments

- public bundles are now retrieved only when needed (i.e. on MissingBundleException when encrypting a message)
- a feedback is given to user when a message is received but it has not been encrypted for our device
- fixed feedback on decryption error if message come from an other device of the client (i.e. it's a carbon copy)
- setBundle if called in a "finally" if republish_bundle is set after decrypting a message

setup.py

@@ -50,7 +50,7 @@ install_requires = [
     'urwid >= 1.2.0',
     'urwid-satext >= 0.6.1',
     'wokkel >= 0.7.1',
-    'omemo >= 0.10.3',
+    'omemo == 0.10.3',  # FIXME: we block to this version until bêta
     'omemo_backend_signal',
 ]