Use DELETE /1/logout to properly logout
Make mail fetch interval in imap service configurable

using environment variable.
Closes: #3409
Use DELETE /1/logout to properly logout
Remove mock dependency since it's no longer needed.
Merge remote-tracking branch 'chiiph/bug/properly_logout' into develop
update coveragerc to bitmask namespace
Merge remote-tracking branch 'chiiph/bug/properly_logout' into develop
Merge remote-tracking branch 'kali/feature/3409_make_imap_poll_configurable' into develop
Merge remote-tracking branch 'kali/bug/remove_mock_dep' into develop
Merge remote-tracking branch 'kali/bug/update_coveragerc' into develop
Remove unused resources path.
Add preferences panel.
Add password change feature.
Add changes file. Closes #2798, #3500.