Place an id on main scope

The external api might be interested to retrieve it
Fix isArethusaLoaded() in external api
Expose scope in eternal api + minor fixes
External plugins need to provide a factory fn
Add list container to external history template
Ugly update of external history plugin
Rename id of arethusa main div
Refactor in main controller
Register plugins in a dictionary in main ctrl

Needs another refactor - not pretty and probably inconsistent.
Copy temp plugin, just to be safe

We are writing to this object when an external plugin is initialized
later! Maybe it's better not to pollute the conf object.
Remove arethusaExternalPlugins

Found a better way to handle this.
Add arethusaInitPlugin

Replaces arethusaExternalPlugin
Add click events to external history

Little buggy right now
Update external history template
Fix minor style issue
Refactor external history plugin