Tracing requests
Custom log factory adds all trace values as one log record parameter (it will be empty if trace values are empty, like in MainThread where there are no incoming requests)
[add] managers/certificate.py with CertificateManger class
[mv] creating self-signed certificate logic into CertificateManger class
[add] renew and days_before_expire methods to CertificateManger class
[mv] several certificate dependent constants to managers/certificate.py
[add] CherryPy BackgroundTask to invoke certificate check hourly (3600 secs)
[fix] tests
[fix] bug with txn timer clean (clean_txn_by_timeout, worker and invoking of it)
