Fix style and grammar in 6.0 announcement

prevent datasource json data stored as nil

closes #14239

run db tests in all packages

Return 404 on user not found

closes #10506

service: fix for disabled internal metrics.

Closes #15715

Explore: Enable click on name label

- click on the name label in a prometheus table was disabled
- it was disabled because every query used to have a metric which is no
longer true
- this change enables it

grafana/ui 6.0.1-alpha.0 release version bump

Need this to be available for plugins

Update of the internal metrics for Grafana was
disabled by mistake when refactoring the code.

Fixes #15651

docs: grafana 6.0 has been released.

moves tracing packge into /infra

moves social package to /login

ref #14679

graph: fixes click after scroll in series override menu

Fixed value dropdown not updating when it's current value updates

moves metric package to /infra

stackdriver: fix for float64 bounds for distribution metrics

stackdriver: change reducer mapping for distribution metrics

Makes changes to dropdown-typeahead2 so that a css
class for the button can be passed in. Means it can
be used instead of dropdown-typeahead.

Switches to using dropdown-typeahead2 for series_overrides
directive and for the influxdb, mysql and postgres datasources
as it already contains a fix for this issue.

This commit also fixes the index property which
was set using an incorrectly spelled length property in the
series_overrides directive.

Closes #15621

ref #14679

- Distribution metrics are now mapped to more reducers
when the metric kind is cumulative.
- The witdth of the metrics dropdown is now much wider.
- Changed the text from Select Aggregation to Select Reducer
to line up with the UI in Stackdriver.

Adds support for explicit distribution metrics and float64 bounds

Fixes #14509

Azure Monitor docs