BLD 1020: Easy access to Group Configurations page from Content Experiment component.

cms/static/js/spec/views/pages/group_configurations_spec.js

cms/static/js/views/group_configuration_item.js

cms/static/js/views/pages/group_configurations.js

common/lib/xmodule/xmodule/split_test_module.py

common/lib/xmodule/xmodule/tests/test_split_test_module.py

.../acceptance/pages/studio/settings_group_configurations.py

common/test/acceptance/pages/studio/unit.py

common/test/acceptance/tests/test_studio_split_test.py

lms/templates/split_test_author_view.html