scripts

* "persistent": effects (e.g. assignments) survive between separate
  remote shell python commands.

* "Python 2.7": because that is what Dogtail needs.

* "per-user": the `dogtail` module must be imported as the user
  running the applications you intend to have Dogtail interact with.

This will allow us to optimize the performance of Dogtail
significantly, as well as reduce the code complexity of the Dogtail
wrapper.

Refs: #12059