add purchace limitations system for rancher - add incentive plans to rancher entries data

apps/core/models.py

@@ -44,3 +44,15 @@ class MobileTest(BaseModel):
     longitude = models.DecimalField(max_digits=22, decimal_places=16)
     count = models.IntegerField(default=0)
     time = models.DateTimeField(auto_now_add=True)
+
+
+class SystemConfig(BaseModel):
+    key = models.CharField(max_length=100, null=True)
+    value = models.CharField(max_length=100, null=True)
+
+    @classmethod
+    def get(cls, key, default=None):
+        try:
+            return cls.objects.get(key=key).value
+        except cls.DoesNotExist:
+            return default