make maps subclassed from plcorebase, add cdnPrefix to maps, prevent map from being bound to multiple things
diff --git a/xos/hpc/models.py b/xos/hpc/models.py
index 1b7535f..2244421 100644
--- a/xos/hpc/models.py
+++ b/xos/hpc/models.py
@@ -78,7 +78,10 @@
 
     def __unicode__(self):  return u'%s' % (self.prefix)
 
-class AccessMap(models.Model):
+class AccessMap(PlCoreBase):
+    class Meta:
+        app_label = "hpc"
+
     contentProvider = models.ForeignKey(ContentProvider)
     name = models.CharField(max_length=64, help_text="Name of the Access Map")
     description = models.TextField(null=True, blank=True,max_length=130)
@@ -86,12 +89,24 @@
 
     def __unicode__(self):  return self.name
 
-class SiteMap(models.Model):
+class SiteMap(PlCoreBase):
+    class Meta:
+        app_label = "hpc"
+
     """ can be bound to a ContentProvider, ServiceProvider, or neither """
     contentProvider = models.ForeignKey(ContentProvider, blank=True, null=True)
     serviceProvider = models.ForeignKey(ServiceProvider, blank=True, null=True)
+    cdnPrefix = models.ForeignKey(CDNPrefix, blank = True, null=True)
     name = models.CharField(max_length=64, help_text="Name of the Site Map")
     description = models.TextField(null=True, blank=True,max_length=130)
     map = models.FileField(upload_to="maps/", help_text="specifies how to map requests to hpc instances")
 
     def __unicode__(self):  return self.name
+
+    def save(self, *args, **kwds):
+        if (self.contentProvider) and (self.serviceProvider or self.cdnPrefix):
+            raise ValueError("You may only set one of contentProvider, serviceProvider, or cdnPrefix")
+        if (self.serviceProvider) and (self.cdnPrefix):
+            raise ValueError("You may only set one of contentProvider, serviceProvider, or cdnPrefix")
+
+        super(SiteMap, self).save(*args, **kwds)