Add release notes for Djblets 1.0.7.

Review Request #10114 — Created Aug. 6, 2018 and submitted — Latest diff uploaded

Information

Djblets
release-1.0.x
08d630b...

Reviewers

This is a small release with some new utilities around form-backed API
resources, a new signal for registry population, a fix for
preserving timestamps in ModificationTimestampField, and a fix for
parsing extension metadata with Unicode characters.

Built the docs. Checked for bad links and spelling errors.