Change EMObservation fields to allow blank

Allow EMObservation fields ra, dec, raWidth, and decWidth to be
blank in forms, resulting in a null database entry.

gracedb/events/migrations/0023_emobservation_fields_blank.py

+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.5 on 2018-06-14 17:19
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('events', '0022_restrict_tag_name_chars'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='emobservation',
+            name='dec',
+            field=models.FloatField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='emobservation',
+            name='decWidth',
+            field=models.FloatField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='emobservation',
+            name='ra',
+            field=models.FloatField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='emobservation',
+            name='raWidth',
+            field=models.FloatField(blank=True, null=True),
+        ),
+    ]

gracedb/events/models.py

@@ -401,12 +401,12 @@ class EMObservationBase(models.Model):
 
     # The center of the bounding box of the rectangular footprints ra,dec
     # in J2000 in decimal degrees
-    ra         = models.FloatField(null=True)
-    dec        = models.FloatField(null=True)
+    ra         = models.FloatField(null=True, blank=True)
+    dec        = models.FloatField(null=True, blank=True)
 
     # The width and height (RA range and Dec range) in decimal degrees 
-    raWidth    = models.FloatField(null=True)
-    decWidth   = models.FloatField(null=True)
+    raWidth    = models.FloatField(null=True, blank=True)
+    decWidth   = models.FloatField(null=True, blank=True)
 
     comment = models.TextField(blank=True)
 

gracedb/superevents/migrations/0009_emobservation_fields_blank.py

+# -*- coding: utf-8 -*-
+# Generated by Django 1.11.5 on 2018-06-14 17:19
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('superevents', '0008_rename_date_created_to_created'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='emobservation',
+            name='dec',
+            field=models.FloatField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='emobservation',
+            name='decWidth',
+            field=models.FloatField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='emobservation',
+            name='ra',
+            field=models.FloatField(blank=True, null=True),
+        ),
+        migrations.AlterField(
+            model_name='emobservation',
+            name='raWidth',
+            field=models.FloatField(blank=True, null=True),
+        ),
+    ]