soft deletes available for applications and environments

- parent relation will not include applications or environments marked
  as deleted
- domain classes will exclude deleted objects from selections
- changed some test factories to use domain_word for resource names,
  because they were using person names and it bugged me

tests/models/test_portfolio.py

@@ -0,0 +1,9 @@
+from tests.factories import ApplicationFactory, PortfolioFactory
+
+
+def test_portfolio_applications_excludes_deleted():
+    portfolio = PortfolioFactory.create()
+    app = ApplicationFactory.create(portfolio=portfolio)
+    ApplicationFactory.create(portfolio=portfolio, deleted=True)
+    assert len(portfolio.applications) == 1
+    assert portfolio.applications[0].id == app.id