Remove stack pointers configuration. Don't use demo_xxxxConf() for it. #27
Description
It's very inconvenient and confusing to configure network stack structure for every [demo] application, moreover if you have several of them it's required to align requirements for the stack configuration; e.g., that hmac is the same for every demo application.
This action should be transparent and clear for the user of a stack. They should instruct emb6 what predefined configuration they would like to use (alternatively provide an API to change this configuration manually).