Fix suggestions being requested with every keystroke

[javierv]

Objectives

• Make suggestions work as intended, sending a request only when users stop typing.

Context

Here's what happens when filling in the budget investment title with "search":

As shown in the image, there are 6 XHR requests, one per keystroke. The test affecting the investments spec randomly sends between 3 and 6 requests (maybe even between 0 and 6).

The relevant code is in suggest.js.coffee:

$this.on 'keyup', ->
  window.clearTimeout(callback)
  window.setTimeout(callback, 1000)

$this.on 'change', callback

The callback is being used as the parameter for the clearTimeout() method; however, it looks like the ID value returned by setTimeout() should be used as the parameter.

Explain why your PR fixes it

By fixing the way clearTimeout() is being used, now the keyup event only generates one request:

Notes

• Originally this PR was also an attempt to fix flaky specs mentioned in Flaky spec: Debates Suggesting debates No found suggestions AyuntamientoMadrid/consul#1429, Flaky spec: Proposals Suggesting proposals No found suggestions AyuntamientoMadrid/consul#1430 and Flaky spec: Budget Investments Phase I - Accepting Suggest Show up to 5 suggestions AyuntamientoMadrid/consul#1431. But travis builds show the tests still fail sometimes.
• Is there a way to add a JavaScript test to the application (maybe using Jasmine?) to make sure this bug doesn't appear again?

[voodoorai2000]

Niiiiice