* update user guide images

* correct a typo

Driud -> Druid

* update the list of supported data sources

* add Presto to supported databases

* update the Google Analytics question

* Update faq.md

* Update faq.md

Fixes deadlinks to http://www.metabase.com/docs/latest/administration-guide/02-setting-up-email.html, which is currently a 404.

Change the recovery instructions to match the new path used in docker
containers.
Include a new section on finding a stopped metabase container.
Make the instructions on using shared/host volumes safe.