Add a UI message for the user to know where to go next.
This message goes away after 60 seconds or right after a MUA logs in.

- Resolves: #7552

from debian stretch on, gpg will be a symlink to gpg2.
this is currently failing if one uses dpkg-divert to make gpg2 provide
/usr/bin/gpg.

this solution just attempts to use gpg2 binary if the search for gpg
binary fails.

- Resolves: #7563
- Releases: 0.9.1

using system tornado library raises a bug due to a mismatching
signature.

- Resolves: #7562
- Releases: 0.9.1

- Resolves: #7542

- Related: #7512

Load flags before creating logger so the logs path considers the
standalone flag.

Move the log file path definition to the function, otherwise it will
calculated during import and (most likely) before defining the
flags.STANDALONE value.

Create logger inside `run_frontend` right after knowing if we are
standalone or not.

- Resolves: #7512

Change KEYS_DIR for a function, so the path does not get defined on
import (and most likely) before the flags are defined.

Move the flags_dict call before the generate_zmq_certificates call.
Otherwise the standalone flag won't be set properly.

- Resolves: #7512

When the error happens too quickly, the errback is called before the
assign of the callLater. And in the errback we cancel that call which
gives an error.

- Related: #7451