set root logging level for acceptance tests to ERROR
Add a request-token to identify which xblock html was rendered as part of the current request

[STUD-2903]
Sync children vertical names with group names in split test module.
Merge pull request #4853 from edx/christina/stud-2093

Add a request-token to identify which xblock html was rendered as part o...
Merge pull request #4838 from edx/clytwynec/remove_warnings_from_lettuce_test_logs

set root logging level for acceptance tests to ERROR
Merge pull request #4777 from edx/anton/sync-groups-and-verticals

Anton/sync groups and verticals
Update selenium and splinter versions