Add files related to last commit

journals/behaviors.py

+from django.core.validators import RegexValidator
+
+doi_journal_validator = RegexValidator(r'^[a-zA-Z]+$',
+                                       'Only valid DOI expressions are allowed ([a-zA-Z]+).')
+doi_volume_validator = RegexValidator(r'^[a-zA-Z]+.[0-9]+$',
+                                      'Only valid DOI expressions are allowed ([a-zA-Z]+.[0-9]+).')
+doi_issue_validator = RegexValidator(r'^[a-zA-Z]+.[0-9]+.[0-9]+$',
+                                     ('Only valid DOI expressions are allowed '
+                                      '([a-zA-Z]+.[0-9]+.[0-9]+).'))
+doi_publication_validator = RegexValidator(r'^[a-zA-Z]+.[0-9]+.[0-9]+.[0-9]{3,}$',
+                                           ('Only valid DOI expressions are allowed '
+                                            '([a-zA-Z]+.[0-9]+.[0-9]+.[0-9]{3,}).'))

journals/migrations/0015_auto_20170408_1758.py

+# -*- coding: utf-8 -*-
+# Generated by Django 1.10.3 on 2017-04-08 15:58
+from __future__ import unicode_literals
+
+import django.core.validators
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('journals', '0014_journal_active'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='issue',
+            name='doi_string',
+            field=models.CharField(db_index=True, max_length=200, unique=True, validators=[django.core.validators.RegexValidator('^[a-zA-Z]+.[0-9]+.[0-9]+$', 'Only valid DOI expressions are allowed ([a-zA-Z]+.[0-9]+.[0-9]+).')]),
+        ),
+        migrations.AlterField(
+            model_name='journal',
+            name='doi_string',
+            field=models.CharField(db_index=True, max_length=200, unique=True, validators=[django.core.validators.RegexValidator('^[a-zA-Z]+$', 'Only valid DOI expressions are allowed ([a-zA-Z]+).')]),
+        ),
+        migrations.AlterField(
+            model_name='publication',
+            name='doi_string',
+            field=models.CharField(db_index=True, max_length=200, unique=True, validators=[django.core.validators.RegexValidator('^[a-zA-Z]+.[0-9]+.[0-9]+.[0-9]{3,}$', 'Only valid DOI expressions are allowed ([a-zA-Z]+.[0-9]+.[0-9]+.[0-9]{3,}).')]),
+        ),
+        migrations.AlterField(
+            model_name='volume',
+            name='doi_string',
+            field=models.CharField(db_index=True, max_length=200, unique=True, validators=[django.core.validators.RegexValidator('^[a-zA-Z]+.[0-9]+$', 'Only valid DOI expressions are allowed ([a-zA-Z]+.[0-9]+).')]),
+        ),
+    ]