Added tests for dependent MWNetworkOps. Re-org of dir structure.

Updated article retrieval to use MWNetworkOp.
Confirmed a new search properly cancels download ops of any previous searches.
Confirmed download progress is being reported.
Added status spinner and confirmed it hides properly.

Change-Id: Ia28590b04b2e036aeadd5cf3c05eddc302dbb9c1
Initial implementation using ops for search with images.

Change-Id: I022dc55f4b89116c8359069b1196b667f25517b0