Add "report" app

- Define ReportTemplate model which contains a report file template

InvenTree/report/migrations/0001_initial.py

@@ -0,0 +1,23 @@
+# Generated by Django 3.0.5 on 2020-05-21 03:43
+
+from django.db import migrations, models
+import report.models
+
+
+class Migration(migrations.Migration):
+
+    initial = True
+
+    dependencies = [
+    ]
+
+    operations = [
+        migrations.CreateModel(
+            name='ReportTemplate',
+            fields=[
+                ('id', models.AutoField(auto_created=True, primary_key=True, serialize=False, verbose_name='ID')),
+                ('template', models.FileField(help_text='Report template file', upload_to=report.models.rename_template)),
+                ('description', models.CharField(help_text='Report template description', max_length=250)),
+            ],
+        ),
+    ]

InvenTree/report/migrations/0002_auto_20200521_0350.py

@@ -0,0 +1,20 @@
+# Generated by Django 3.0.5 on 2020-05-21 03:50
+
+import django.core.validators
+from django.db import migrations, models
+import report.models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('report', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='reporttemplate',
+            name='template',
+            field=models.FileField(help_text='Report template file', upload_to=report.models.rename_template, validators=[django.core.validators.FileExtensionValidator(allowed_extensions=['html', 'tex'])]),
+        ),
+    ]