Show the tree marker when selecting a tree

The statefulness of the plot marker is pretty odd but at this point I
don't feel comfortable enough to change it on the eve of a release.
Hide advanced search UI when search is executed

fixes #1245 on github
Change instance fields schema in API

This changes accomplishes two goals

- Supports explicitly defining the order in which fields appear
in mobile apps

- Makes the instance API more useful beyond our mobile needs.
All readable fields are now returned with the instance, not
just the ones used by the mobile application.

This is the new, expected schema of the the mobile_api_fields
value in the instance config

[
  {
    'header': 'Tree Information',
    'field_keys': ['tree.species', 'tree.diameter', 'tree.height']
  },
  {
    'header': 'Plot Information',
    'field_keys': ['plot.width', 'plot.length']
  }
]
Merge pull request #1249 from OpenTreeMap/fix/show-tree-marker-for-trees

Show the tree marker when selecting a tree
Merge pull request #1252 from steventlamb/bug/1245_retract_advanced_search

Hide advanced search UI when search is executed
Update form tag to support MultiPolygon fields

There are now green infrastructure fields that have MultiPolygons as
their type.
Merge pull request #1253 from jwalgran/topic/change-instance-info-api-schema

Change instance info API schema