Update + sync with comments in 'default controller
Updated docs/comments for to_nexson method.
Merge branch 'merge-otus-and-refresh' of github.com:OpenTreeOfLife/opentree into merge-otus-and-refresh
Refactored element-ID logic, gathering funcs, etc.

Moving lots of common logic (per NexSON element type) to the viewModel,
along with other ephemeral data that gets cleared when the load a fresh
NexSON study.
Separate complete element IDs and ordinal numbers.

Refactor and rename the JS functions for reckoning available element IDs
(by type), and provide separate methods to work with just the ordinal
number. For example, 'edge214' vs 214. This was needed for compatibility
with NCLconverter.
Merge pull request #252 from OpenTreeOfLife/merge-otus-and-refresh

Merge otus and refresh (cont'd)