delay creation of polling background thread until contexts have been
created for all pre-existing apps, so as to prevent a deployment race
condition.

@andyberry88 can you make sure you're happy with this change, as you may
have had reasons for the start-up order we previously had?
create blade and bladeset specific version of the js-test-driver
templates since the plugin path is different.
Merge branch 'brjs-wip-presenter-workbenches' of git@github.com:BladeRunnerJS/brjs.git into brjs-wip-presenter-workbenches