add the single-transaction option in restore

[ramonskie]

currently when we have some intermittent issues when restoring our database.
this would be solved when we add the single-transaction option to
https://github.com/cloudfoundry/postgres-release/blob/develop/jobs/bbr-postgres-db/templates/restore.sh.erb#L34

would you consider accepting a PR?

1. single-transaction by default
2. single-transaction as optional

[cf-gitbot]

We have created an issue in Pivotal Tracker to manage this:

https://www.pivotaltracker.com/story/show/170995484

The labels on this github issue will be updated when the story is started.

[valeriap]

@ramonskie A PR is welcome.
The good of this option is that any error would rollback the entire restore.
Anyway this is also a drawback if you are restoring a big database and the restore would last hours.
For this reason I would prefer it to be optional.

[valeriap]

@ramonskie Thanks for the PR.
I plan to create a new release containing your commit as soon as the new PostgreSQL release will be available (planned for February 13th).

[ramonskie]

you are awsome and thanks for your patience

[valeriap]

Release v41 created.