Use more appropriate fields instead of TextFields

Fix issue #72

infoscreen/migrations/0005_auto_20170913_1841.py

@@ -0,0 +1,25 @@
+# -*- coding: utf-8 -*-
+# Generated by Django 1.11 on 2017-09-13 15:41
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('infoscreen', '0004_videoinfoitem'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='externalimageinfoitem',
+            name='url',
+            field=models.URLField(),
+        ),
+        migrations.AlterField(
+            model_name='externalwebsiteinfoitem',
+            name='url',
+            field=models.URLField(),
+        ),
+    ]

infoscreen/models.py

@@ -97,7 +97,7 @@ class ApyInfoItem(InfoItem):
 
 class ExternalWebsiteInfoItem(InfoItem):
     display_name = _("External website")
-    url = models.TextField()
+    url = models.URLField()
 
     def get_template_url(self):
         return "/static/html/external_website.html?url={}".format(self.name)
@@ -213,7 +213,7 @@ class HslInfoItem(InfoItem):
 
 class ExternalImageInfoItem(InfoItem):
     display_name = _("External image")
-    url = models.TextField()
+    url = models.URLField()
 
     def get_template_url(self):
         return "/static/html/generic_image.html?img={}".format(self.name)