Moved Add Config Option modal to tray

This also fixes a few things.
- validation is cleaned up a bit
- the typeahead option now properly works again for sections.

Closes COUCHDB-2443
Hmmm... true... but it'll mean one extra (and technically redundant) line of code to cancel the event in `processKey` as well as `createConfigOption`. But agreed, it'd be looser coupled. Adding!