backport postgres improvements

[ltalirz]

fix #1382

backport improvements to postgres to deal with postgres setups without
sudo.

• update yapf to recent version

[coveralls]

Coverage increased (+0.008%) to 55.8% when pulling 2be7f33 on ltalirz:issue_1382_quicksetup_without_sudo into d8f8ff1 on aiidateam:release_v0.12.3.

[ltalirz]

@sphuber tests pass, just coverage fails - ready to be reviewed.
btw - here I guess you still make sense as a reviewer; for the next two small PRs I'll put other people