Add event logging

[allison-li-1016]

Estimated time to review: small

Addresses #191

Description of changes:

• added CLI option for logging events
• added an 'EVENTS' output file logging events that occur at given tick intervals
• added logging information to cytotoxic module to track lysis events & proliferation module to track division events and cycle length
• edit tests to include new mocks for event logging

Discussion:

• We can consider logging division as an event as a proxy for cell cycle durations
  • Then we would just need to add logging into the proliferation state module instead of changing all the cell containers as mentioned in Adding and logging cell cycles #206
• I am concerned about the events queue object getting exponentially larger if we start tracking frequent events, we should discuss clearing the queue once the events are logged

[Jannetty]

Recording that we spoke about making sure to clear the events queue object each time it writes to file

[kristaphommatha]

LGTM!

[allison-li-1016]

@allison-li-1016 consider adding eventLog object in the Utils class to enforce logs to be of a certain format....