This app is example of how to accept Ethereum ERC20 compatible tokens on ICO.

Logic of function is next - user, which want to participate in ICO for ERC20 compatible Ethereum token (like FirstBlood or Chronobank) must invoke allow function for himself on original paybale token contract and then
invoke buyforTokens function on ICO contract. This function is checked for allowance from paybleToken contract, then it invoke transferFrom function to ICO contract and provide buy ICO tokens.