Update ixmp.jar and add postgres JDBC driver

[zikolach]

• ixmp.jar updated to most recent one
• added PostgreSQL JDBC dependency

How to review

• look at the list of changes https://github.com/iiasa/ixmp_source/compare/b6812f206b03ed3f3a849cdf299a91c0230ffc26...0f825c62879fc0600f357a5e14d19c5b90723335

PR checklist

• Tests added.
• Documentation added.
• Release notes updated.

[khaeru]

@zikolach now that #182 is in, can you force-push this branch (with no changes) to trigger a CI restart?

[zikolach]

@zikolach now that #182 is in, can you force-push this branch (with no changes) to trigger a CI restart?

Rebased on top of current master

[khaeru]

All green, so seems good to go!

It would be nice to create an issue to add some tests on the Python side demonstrating PostgreSQL functionality.

[zikolach]

All green, so seems good to go!

It would be nice to create an issue to add some tests on the Python side demonstrating PostgreSQL functionality.

@khaeru thanks for merging. We need to think also about running tests on oracle as currently we run them only using hsqldb. But maybe that's more related to testing java code - as db support isn't exposed anyhow to python.