[bug 766394] Fixed template spacing.
[bug 766394] Added migration for  migrations user.

This is the user we should use for data migrations when having
to assign owners/creators to new objects.
[bug sharelink-766394] Share links data migration.

This is a data migration for share links. If the template tag
sharing a link is found in the most recent revision for a document,
we then create a new revision based off the most recent one with
content that excludes the share link.