* add fixtures to conftest.py
* use fixtures in test_appctx.py
* use fixtures in test_blueprints.py
* use fixtures in test_depreciations.py
* use fixtures in test_regressions.py
* use fixtures in test_reqctx.py
* use fixtures in test_templating.py
* use fixtures in test_user_error_handler.py
* use fixtures in test_views.py
* use fixtures in test_basics.py
* use fixtures in test_helpers.py
* use fixtures in test_testing.py
* update conftest.py
* make docstrings PEP-257 compliant
* cleanup
* switch dictonary format
* use pytest parameterization for test_json_as_unicode
When an exception has been handled when using the request / app context in a with statement, `sys.exc_info()` will still contain the exception information even though it has been handled already. The `__exit__` methods pass in `None` for the exception value in that case, which needs to be distinguisable from the default value for the `exc` parameter. Use a dedicated singleton sentinel value instead.
