[HELPERS] add license
[HELPERS] add GenerateCert to generate pem files for TLS
make format
[HELPERS] add CreateDirectoryIfNotExists()
[HELPERS] add ValidateListenAddress()
[WLAPP] refactored picnic, rucksack structs and changed CLI args
[PICNIC|RUCKSACK] refactored tempdir
[HELPERS] renamed DirExists to PathExists