Allow configuring of async call timeout

[jmartasek]

At the moment almost all of the external calls have timeouts of 30000 ms and these are hard-coded in the calls. For testing scenarios on less than beefy hardware I need to be able to configure it.

[ianwdunlop]

It could be added as a param when you construct the main 'search' object as well as the API URL, app id and key. Will also need a corresponding param passed in to the explorer so that it can send it to ops.js