add basic scaffold of scenarios, including the ability to add agents to scenarios, edit scenarios, and view scenarios.  next step: import and export
Merge remote-tracking branch 'origin/master' into scenarios
Merge branch 'master' into scenarios

Conflicts:
	app/assets/stylesheets/application.css.scss.erb
	app/views/agents/index.html.erb
	app/views/agents/show.html.erb
Scope menu
Merge branch 'master' into scenarios
better handling of return paths, and more specs
Merge branch 'master' into scenarios
allow exporting of a set of Agents with their links from a Scenario; Scenario guid is now generated and copied to export, as well as a source link when public
easier removal of agents from scenarios via the menu
Merge remote-tracking branch 'origin/master' into scenarios
diagram links back, export URL includes .json
upload and fetch by url, data object manages import; next step is actual import
Solves #357 #359
Solves #354
Fix spec
Add simple MQTT support to subscribe to, publish messages.
Tweak wording
Assume the payload is going to be JSON
Indent description
Add presence validation