Update tree fields for OTM2

 - Remove fields not longer present (we intend to support these via UDFs)
 - Split address into street, city, and zip
Exclude the tree being updated from the proximity check

If an opentreemap id number is passed in we update the tree rather than
creating a new one.

Thus, we need to exclude that tree from the proximity check, or it will
always fail.
Remove TODO
Merge pull request #1778 from maurizi/tree-import-backend

Tree import backend