Autocomplete from GIS list of CRSs..

..using django-autocomplete-light, in both the admin area and the
end-user form

Closes #32

apps/map/models.py

@@ -1,17 +1,32 @@
 import datetime
 from urllib import parse
+
 from django.contrib.gis.db import models
 from django.contrib.auth.models import User
-from django_extensions.db.fields import AutoSlugField
-from django_countries.fields import CountryField
+from django.db import connection
 from django.utils.translation import ugettext as _
 from django.template.defaultfilters import slugify
+
+from django_extensions.db.fields import AutoSlugField
+from django_countries.fields import CountryField
 from multiselectfield import MultiSelectField
 from phonenumber_field.modelfields import PhoneNumberField
 
 from . import validators
 
 
+class SpatialRefSys(connection.ops.spatial_ref_sys()):
+    def __str__(self):
+        return self.__unicode__()
+
+    def __unicode__(self):
+        return '{0.auth_name}:{0.auth_srid} {0.name}'.format(self)
+
+    class Meta:
+        proxy = True
+        verbose_name = "spatial reference system"
+
+
 class Shapefile(models.Model):
     file = models.FileField(
         upload_to='shapefiles/',
@@ -1007,13 +1022,9 @@ class CaseStudy(models.Model):
     )
 
     # 4.3.2
-    coordinate_reference_system = models.CharField(
-        verbose_name=_("Coordinate reference system"),
-        help_text=_("Enter the coordinate reference system of the shapefiles."),
-        max_length=12,
-        default=None,
-        null=True,
-        blank=True
+    coordinate_reference_system = models.ForeignKey(
+        SpatialRefSys, null=True, blank=True,
+        default=4326
     )
 
     # 4.3.3