WIP: Updating to 5.2.1

[nathansamson]

This is a WIP to update to 5.2.1 and as well to reduce the slug size.

Note that this version is untested (I did not update the deps yet for example) so this might not work at all yet.

I will amend commits as I go along, this is just to let anyone know I am working on this

[nickbayley]

@nathansamson

Heya, I thought it would be worth trying out your PR in-case it reduced the slug-size enough to get my app running. Unfortunately it didn't, but my slug size did go from 352.7M to 334.3M.

Now waiting on Heroku support to hopefully increase my slug limit.

[nathansamson]

Note that I had problems with this version of LO in my use case (opening / converting word documents had an ugly bug).

[nickbayley]

That's cool. Heroku have upped my limit now, so I'm back to master. Cheers for the heads up!