Add logging from casting voting to tally

[algomaster99]

This would be useful in comparing the logs of the verified backend and unverified backend. We are not sure what the logs will contain. We have to decide what events to log.

• timing information is critical
• log statements should contain a piece of session information. Basically, we should be able to distinguish a set of events in a particular session.
• logging could be set to 0:DEBUG.

The goal of comparing logs is to see if both backends are working correctly and if they are doing something abnormal.

cc @arolle @palmskog