a) All classes will use message class to create messages
b) All classes will put the messages in instance of SJError
c) If a method of a class adds a message, it will return instance of SJError not true or false
d) All admin show form functions will show messages of SJError at the top

Naming conventions 
- Class name starts with SJ_
- Function name starts with share_juice_
- HTML ID/classes are represented as share-juice-this-id ( not _ )