Change permissions on backup files - #2
Use more restrictive permissions for backup tar files and for the db, uploads, and repositories directories inside the tar files. See #1894. Now the backup task recursively `chmod`s the `db/`, `uploads/`, and `repositories/` folders with 0700 permissions, and the tar file is created as 0600.
This is a followup to !1703, which was reverted because it broke Rspec tests. The test failures were due to the rake task changing directories and not changing back, which I fixed with this commit.
cc @sytse
See merge request !1716