add a first stab at an experimental PSKC output format

this is clearly a naive least-effort implementation..
relates to #4
implement secret key in base64 for logging

specifically for the pskc format
close the logFile when things change
register aboutToQuit() handler and call closeLogFile() there
write start and end of PSKC info
user serial:slot for Key@Id
add tokenLength formatter to get responseFormat correct
add CryptoModuleInfo with configSlot
fixup xml syntax