IF: HotStuff code cleanup

[arhag]

• Address style inconsistency
• Remove extraneous comments
• Easy optimization (address pass-by-value arguments)
• Change unit tests that could easily run in parallel so that they run as part of our parallelizable tests.

[heifner]

• Fix all warnings
• Verify all TODOs have been addressed

[greg7mdp]

• Use compact namespace syntax: namespace eosio::chain { ... };

[arhag]

Overcome by events.