First batch of renaming "test" to "scenario"

At this point we still keep separate "test" and "scenario"
versions of the data, but all tests pass.
Trivial refactoring: rename variable
Adapt the admin interface to the test->scenario rename
Simplify the scenario admin interface

Drop the "Actions" column and make the "State" column contain
buttons to toggle the state (much like the recent change in the
head admin interface).
Show a message on admin UI when no scenarios are available

* While at it, fix a bug that made the "*current-scenario*"
  pseudo-plugin end up with a broken internal structure.
* The fix needed a small refactoring of plugin internal
  structure code to be sane.
Fix and clean-up examples

* Adapt and rename the scenario example
* Fix "simple-streaming" example (was using old API for events)
Trivial clean-ups (mostly jshint)
Allow whitespace in scenario names