don't log more information than is needed in browserid-metrics.json - strip everything from referrer except origin - issue #1283

log x-real-ip rather than remote ip in metrics stuff to get the proper ip in anonymous metrics logs.  closes #391

rename 'log_path' configuration variable to 'var_path', as now it will be the path to all files created at runtime.  issue #172

rather than imposing restrictions on structure of logged objects we should make all required fields proper parameters that are obvious upon inspection of the signature of the log function. issue #168

(mysql driver) add logging, implement emailsBelongToSameAccount, addKeyToEmailRecord, checkAuth, and pubkeysForEmail