Move integration images into a subdirectory.

Review Request #9800 — Created March 17, 2018 and submitted — Latest diff uploaded

Information

Review Board
release-3.0.x
4f90292...

Reviewers

We're going to be having a lot of new screenshots for integration docs.
Currently, screenshots live in admin/integrations/, but this is
cluttering things up. This change moves all integration images into an
images/ subdirectory.

Built the docs and checked that all images showed up.