test requirements: Update hypothesis to 3.4.2

- Test functions defined using @given can now be called from other
  threads
- Attempting to delete a settings property would previously have
  silently done the wrong thing. Now it raises an AttributeError.
- Creating a settings object with a custom database_file parameter was
  silently getting ignored and the default was being used instead. Now
  it’s not.

misc/requirements/requirements-tests.txt

@@ -7,7 +7,7 @@ decorator==4.0.10
 Flask==0.10.1  # rq.filter: < 0.11.0
 glob2==0.4.1
 httpbin==0.4.1
-hypothesis==3.4.1
+hypothesis==3.4.2
 itsdangerous==0.24
 # Jinja2==2.8
 Mako==1.0.4