Updating screenshots from submodule

.gitattributes

.travis.yml

.../UI/expected-screenshots/ActionsDataTable_auto_expand.png

...I/expected-screenshots/ActionsDataTable_column_sorted.png

...d-screenshots/ActionsDataTable_exclude_low_population.png

tests/UI/expected-screenshots/ActionsDataTable_flattened.png

tests/UI/expected-screenshots/ActionsDataTable_initial.png

...ted-screenshots/ActionsDataTable_pageview_percentages.png

tests/UI/expected-screenshots/ActionsDataTable_search.png

...ed-screenshots/ActionsDataTable_segmented_visitor_log.png

...eenshots/ActionsDataTable_segmented_visitor_log_hover.png

...xpected-screenshots/ActionsDataTable_subtables_loaded.png

.../UI/expected-screenshots/ActionsDataTable_unflattened.png

...eenshots/ActionsDataTable_unique_pageview_percentages.png

tests/UI/expected-screenshots/BarGraph_load.png

.../UI/expected-screenshots/BarGraph_metric_picker_shown.png

tests/UI/expected-screenshots/BarGraph_other_metric.png

...xpected-screenshots/CoreUpdaterCode_httpUpdateSuccess.png

.../expected-screenshots/CoreUpdaterCode_httpsUpdateFail.png

...enshots/CoreUpdaterDb_CoreUpdater.API.ErrorMessageCSV.txt