added blog subscriber, unsubscribe

erpnext/website/page/blog/blog.py

@@ -0,0 +1,11 @@
+import webnotes
+def subscribe(arg):
+	"""subscribe to blog (blog_subscriber)"""
+	if webnotes.conn.sql("""select name from `tabBlog Subscriber` where name=%s""", arg):
+		webnotes.msgprint("Already a subscriber. Thanks!")
+	else:
+		from webnotes.model.doc import Document
+		d = Document('Blog Subscriber')
+		d.name = arg
+		d.save()
+		webnotes.msgprint("Thank you for subscribing!")