Fix deprecation warnings for Django 1.11 and Django 2.0.

Signed-off-by: Roberto Rosario <roberto.rosario.gonzalez@gmail.com>

mayan/apps/sources/models.py

@@ -419,7 +419,7 @@ class IntervalBaseModel(OutOfProcessSource):
         DocumentType,
         help_text=_(
             'Assign a document type to documents uploaded from this source.'
-        ),
+        ), on_delete=models.CASCADE,
         verbose_name=_('Document type')
     )
     uncompress = models.CharField(
@@ -509,14 +509,14 @@ class EmailBaseModel(IntervalBaseModel):
         MetadataType, blank=True, help_text=_(
             'Select a metadata type valid for the document type selected in '
             'which to store the email\'s subject.'
-        ), null=True, related_name='email_subject',
+        ), on_delete=models.CASCADE, null=True, related_name='email_subject',
         verbose_name=_('Subject metadata type')
     )
     from_metadata_type = models.ForeignKey(
         MetadataType, blank=True, help_text=_(
             'Select a metadata type valid for the document type selected in '
             'which to store the email\'s "from" value.'
-        ), null=True, related_name='email_from',
+        ), on_delete=models.CASCADE, null=True, related_name='email_from',
         verbose_name=_('From metadata type')
     )
     store_body = models.BooleanField(
@@ -767,7 +767,8 @@ class WatchFolderSource(IntervalBaseModel):
 
 class SourceLog(models.Model):
     source = models.ForeignKey(
-        Source, related_name='logs', verbose_name=_('Source')
+        Source, on_delete=models.CASCADE, related_name='logs',
+        verbose_name=_('Source')
     )
     datetime = models.DateTimeField(
         auto_now_add=True, editable=False, verbose_name=_('Date time')

mayan/apps/sources/views.py

@@ -1,9 +1,9 @@
 from __future__ import absolute_import, unicode_literals
 
 from django.contrib import messages
-from django.core.urlresolvers import reverse, reverse_lazy
 from django.http import HttpResponseRedirect, JsonResponse
 from django.shortcuts import get_object_or_404
+from django.urls import reverse, reverse_lazy
 from django.utils.encoding import force_text
 from django.utils.translation import ugettext_lazy as _
 
@@ -232,7 +232,7 @@ class UploadInteractiveView(UploadBaseView):
                 if forms['document_form'].cleaned_data['document_type_available_filenames']:
                     label = forms['document_form'].cleaned_data['document_type_available_filenames'].filename
 
-            if not self.request.user.is_anonymous():
+            if not self.request.user.is_anonymous:
                 user_id = self.request.user.pk
             else:
                 user_id = None
@@ -372,7 +372,7 @@ class UploadInteractiveVersionView(UploadBaseView):
             except Exception as exception:
                 messages.error(self.request, exception)
 
-            if not self.request.user.is_anonymous():
+            if not self.request.user.is_anonymous:
                 user_id = self.request.user.pk
             else:
                 user_id = None

mayan/apps/sources/wizards.py

@@ -1,8 +1,8 @@
 from __future__ import unicode_literals
 
 from django.contrib import messages
-from django.core.urlresolvers import reverse
 from django.http import HttpResponseRedirect
+from django.urls import reverse
 from django.utils.encoding import force_text
 from django.utils.http import urlencode
 from django.utils.translation import ugettext_lazy as _