Summary: This moves the interesting parts of D505 into the core, so other components can use them as well.

Test Plan: `make test`

Reviewers: ardumont, seirl, #reviewers

Reviewed By: ardumont, #reviewers

Subscribers: douardda

Differential Revision: https://forge.softwareheritage.org/D507

- add classifiers informations,
- add the content of the README file as long_description,
- add configure_urls.

related to T1242

note that unit tests are executed via pifpaf, so a running postgres
server is not required (nor used) when unit tests are spawn with tox.

Also add .tox in gitignore.

Related T1061

Summary:
when ON_ERROR_STOP is not set, dumps can restore even if there's a
syntax error. That's not really a sensible thing to do.

Also add --no-psqlrc because my psqlrc has stuff in it that makes psql noisy in
batch mode (\timing).

Test Plan:
Run the swh-vault tests, which are the only ones to use this fixture
in this mode

Reviewers: #reviewers!

Differential Revision: https://forge.softwareheritage.org/D307

Related T1036

Related T1036

change cherry picked from python module template
commit 71b117ba0cf9f1251b1cac26d0994df03a4c787d

This will help create new logging handlers.

Related T700

The previous behavior would try catching the builtin ConnectionError, that
requests never raises.

Related T646

Related T646

Related T646