Introduce budget, reimbursements for expenses

[raucao]

This is a big one. It isn't linked from the dashboard yet, but you can browse to /budget and propose reimbursements from there.

Requires https://github.com/67P/kredits-contracts/pull/198 Refs 67P/kredits-contracts#48

To do

• [x] Fix ember linting errors
• [x] Sync new and missing reimbursements from network when cached data loaded
• [x] Fix cache loading after adding new reimbursements (records shows up twice)
• [x] Fix bug, which claims expense amounts are missing, after tx creation

[raucao]

I just finished the functionality of the PR, so there are just the linter errors left. You can test it on your machines now.

There's one known issue, which won't be much of a problem in a production: a race condition, when your tx confirms within the loading of the reimbursement list after pressing the submit button on the reimbursement form. I'm not sure how to handle that, and it doesn't break anything in the unlikely case that you see this in production. Just reload the page and all is good, due to the caching and syncing logic.

I would recommend to always add a block time to your local devchain when testing UI anyway, to not get the wrong feel for how things work in production: e.g. npm run devchain -- --block-time 5.

[raucao]

All done and ready to merge from my point of view.

[raucao]

@galfert Did you see my replies? I just merged the corresponding contracts PR, so it'd be great if we can merge this one as well now.