Set the Protocol Fees using the RLN contract constructor instead of hard coded

[kgrgpg]

Protocol fees has been implemented and hardcoded to 20% of the membership deposit as explained in #5 . This method works well as a reference to show the calculations involved using the WAD. There might also be some gas cost savings involved.

But there is a requirement to pass the percentage as a parameter in the constructor for easy deployment of contract. But should this be considered, since passing the fees as parameter would result in lower visibility to the contract readers.