Clean up imports
Add an endpoint for getting instance info for maps near a point
Merge pull request #996 from maurizi/topic/instanceListForPoint

Instance list for point
Include advanced search configuration in instance info API endpoint
Merge pull request #998 from maurizi/topic/advancedSearchApiInfo

Advanced search API info
Fix broken migration
Add more information to instance info endpoint

Most of what we want is similar to the "form_extras" tags that we use in
our templates so part of this commit refactors for edits to share code
directly with the API.

This also fixes an bug where a model without an instance but with unit
data would crash the template tags.