API comparison

Initial commit for the API comparison script. 

A test script has been added that executes a combined search between all the specified API's in the `tests.json` file and outputs the results. This allows us to compare the returned results and check whether or not they match the expected results.
I needed quite some time to wrap my head around what was going on here, one of the reasons being that a lot of functions do a lot more things than their names initially make out. For example 
* `_createGlobalInformation` also calls the callback passed to `getResults` when it's finished
* `_doCreateResourceModel` calls `_createResourceModel` but in the callback also `_getFacets` and `_createGlobalInformation`

Could you refactor this so you'd have multiple small functions each doing one single thing, and have `getResults` call each of these before calling the passed callback itself? Ideally a function should only be doing the single thing you named it to do, if you see that it grows into doing more things that probably means things need to be separated out a bit more.