Remove djsonb dependency and move its relevant logic into Grout core

CHANGELOG.md

@@ -5,6 +5,9 @@
 Changes we're making en route to version 2.0. When we cut a release, this
 section will form the changelog for v2.0.
 
+- Add support for Django 2.0 ([#8](https://github.com/azavea/grout/pull/8))
+- Removed external `djsonb` dependency and moved its lookup logic into
+  Grout core ([#7](https://github.com/azavea/grout/pull/7)
 - Removed extraneous location fields from the `Record` data model (
   [#5](https://github.com/azavea/grout/pull/5)), including:
     - `city`

grout/filters.py

@@ -7,6 +7,7 @@
 from django.core.exceptions import ImproperlyConfigured
 from django.contrib.gis.db import models as gis_models
 from django.contrib.gis.gdal.error import GDALException
+from django.contrib.postgres.fields import JSONField
 from django.db.models import Q
 
 from rest_framework.exceptions import ParseError, NotFound
@@ -16,12 +17,10 @@
 from grout.models import Boundary, BoundaryPolygon, Record, RecordType
 from grout.exceptions import QueryParameterException
 
-from djsonb import fields as jsb
-
 
 # Map custom fields to CharField so that django-filter knows how to handle them.
 FILTER_OVERRIDES = {
-    jsb.JsonBField: {
+    JSONField: {
         'filter_class': django_filters.CharFilter
     },
     gis_models.PointField: {