R1:da3be5071ba7

Give "delete Repository" a disabled style

Summary: Some discussion on IRC. This is more consistent with other disabled items, which are click-to-explain.

Test Plan: Viewed UI, clicked link.

Reviewers: btrahan, dctrwatson, asherkin

Reviewed By: asherkin

CC: aran

Differential Revision: https://secure.phabricator.com/D7857