Bookshelf & Knex upgrade

[ErisDS]

Bookshelf & knex did not get upgraded at the start of this release cycle. This was because there was a reasonable amount of work to do, and I got carried away with other work before I completed it. I very much regret this, as several of the filter, include, etc features I've been building into our model layer would have been simpler had I had access to the newer features.

I did try out upgrading to [email protected] & [email protected], it did not cause any test regressions (and iirc I ran the old casper.js test suite against this). The current versions are [email protected] and [email protected], and so there's been another significant update which warrants testing.

• Update bookshelf
• Update knex

At the start of the next release cycle, I want to get this upgrade done ASAP. I'll be using this issue to document everything that I know can or needs to be changed as a result of the upgrade.

• Bookshelf now has a serialize method that is called by toJSON. It should be possible to use the new structure to override serialize instead of toJSON in places in our codebase, and simplify our code.
• Bookshelf now has count methods which may be useful
• Knex has a new modify method that should make it easier to construct complex query builders from pre-defined parts.
• Knex should be getting a new countDistinct method we can use to replace some horrible knex.raw code in the pagination plugin (should be in knex 0.9.1)
• Knex now supports nested transactions, may be useful for improving our post & tag saving code
• Knex has had significant improvements to the join syntax which we may be able to leverage

Even newer:

• Bookshelf has got a pagination plugin and a fetchPage method that we can use instead of our own.

Things to be aware of:

• The pool handling software has changed completely in knex since 0.7. There are some open issues around pools and so some significant testing might be in order.

[mikebaldry]

Really need this, with a non-perfect PG connection, current version of knex just crashes the whole app any time a connection dies, instead of closing it and reconnecting. This is now handled nicely in 0.8.6

[ErisDS]

The library updates are done, but none of the code changes / potential improvements are done yet.

[ErisDS]

Bookshelf 0.9.5 (merged by #6836) has its own pagination plugin (finally!) it may be worth looking at dropping ours in favour of theirs.

[ErisDS]

Can close this. Bookshelf is actively maintained again, and at some point we'll look into catching up again. When we do, this information is here. Right now the built in fetchPage doesn't seem stable, so should stick to our own implementation for a bit longer probably.