Addd waitForPending update method

[ppamorim]

This PR removes the usage of Thread.sleep(timeInterval:) included between async calls. I tried to implement a solution based on DispatchSemaphore but this turns out to be problematic when used inside closures and it was creating a deadlock.

[ppamorim]

bors try

[bors]

try

Build succeeded:

• swift-test

[bidoubiwa]

I changed two things in this review

1. As the update routes give information about a process and not a result, I changed ResultType for ProcessType.
2. In all other SDK's it is waitForPendingUpdate and not waitForPendingUpdate so I changed it! :)

[curquiza]

Should be merged after #71

[curquiza]

@ppamorim, there are conflicts, sorry but we cannot use Bors here for the moment 😕 You need to rebase your branch.

[ppamorim]

@curquiza I will do this after we merge #72.

[ppamorim]

bors try

[bors]

try

Build succeeded:

• swift-test

[curquiza]

Great addition! Thanks!

[curquiza]

bors merge

[curquiza]

@ppamorim is this PR breakable because you change public let number: Int into public let number: Int? in Update model? Not a big deal, just to know.

[bors]

Build succeeded:

• swift-test

[ppamorim]

@curquiza This is a required change because the update result may not return the number field. Before this the test was crashing.