ENH: Run all tests using the TubeTK launcher to set the correct environment.

Change-Id: Iab21a78fe2bbfdd39f0650c95ae26853a62b8f1d
ENH: Build tests as CLI using SlicerExecutionModel

Change-Id: I7ea429104867510ca7b6bf9c05a6237b3184ecda
Merge pull request #173 from chrismullins/fix-extension-tests

Fix extension tests.