Cancellable search requests

[ara4n]

Search requests can take a long time. We need to be able to cancel the JS SDK promise - either using something like bluebird cancellable promises, or extending the JS SDK to have a cancelSearch method a bit like the cancelUpload method.

[grahamperrin]

As far as I can tell, this is largely implemented:

1. whilst the magnifying glass pulses
2. click the nearby X

[aaronraimist]

Yes this seems to be fixed

[t3chguy]

the issue says to cancel the underlying js-sdk request, given we recently discarded bluebird and that wasn't used for cancellations then I doubt it actually gets cancelled

[kittykat]

@t3chguy I can't reproduce this (seems to be cancelable), can you confirm that this is an ongoing issue?

[t3chguy]

Just because the UI looks cancelled, doesn't mean the API request is.