Panel errors

Moved AlertTab and StateHistory to app/features/alerting

fix: When loki is default data source, datasource is passed as undefi…

Fix stackdriver aggregation series merge

14722 - removing unnecessary arn check that breaks assume role featur…

Remove the jump effect on run query button

Caused by the return and loading spinner icons having different widths. Used fa-fw helper class to ensure fixed width on icons. Also, made the spacing between icon and button label slightly smaller, as the rotated level-down icon used as return icon has significantly smaller width compared to the loading spinner and it looked oddly far from the label as compared to timepicker's icon

# Conflicts:
#	public/app/features/dashboard/dashgrid/DataPanel.tsx

Fixed new gometalinter issues

fix JSON in responses for Admin API documentation

Fixed issue with cut legend in firefox & mobile devices, 

Some cleanup