Adding unit tests for auto completion of Numpy, Scipy and pandas

[DonJayamanne]

As we've had issues with intellisense for numpy and scipy, would it be worth adding some tests for these.
I've noticed that we've had some issues (upstream) in PTVS analysys engine too.

@MikhailArkhipov cc

Please feel free to close this if you deem it to be unncessary.

[DonJayamanne]

Closing as language server testing is done in a separate repo.