Use window.requestAnimationFrame() instead of timeouts

[slaweet]

Actual behaviour

We are setting timeouts (usually 20 seconds) in various components to re-check for things like:

• latest transactions
• account balance
• delegates
• votes

Expected behaviour

As @alihaghighatkhah pointed out, we should be using window.requestAnimationFrame() because it triggers only when the window is visible, so it can save a lot of traffic.
Although, we must implement a function that determines whether it makes sense to repeat a particular request. It would be nice if it could somehow synchronise with block time so that it knows that a new block has been forged and thus there can potentially be some changes.

Maybe we can use this angular wrapper:
https://www.npmjs.com/package/angular-raf