With this change a blame column is added to the left side of diff
tables. The column is empty and hidden until blame is loaded. A button
is added to the change view to trigger a load of the blame for that
diff, as well as a unload it if already loaded. In this stage, the blame
information is non-interactive and only displays the SHA, date and
commit author.
Feature: Issue 6075
Change-Id: Ifcb951265d0e6339094e6b7c9574ec9c69e60b51