Some changes to the staking system and governance

The Comet release replaces the current double tier reward system with a single-tier block reward system in which everyone can stake, even existing Service Nodes. This results in a less fragile network by removing the mechanism that pays rewards to Service Nodes, it increases the security of the blockchain by enabling Service Nodes to stake which increases the number of stakers on the network by about 180%, and it stabilizes the support for services by removing the mutual exclusivity of staking and operating a Service Node. Finally, the Comet release offers greater performances as the system allows dramatically less bandwidth requirements and thus more people to participate in the network by being able to run the wallet with fewer resources, which produces a more stable network. The separation of the governance system and Service Nodes also opens voting to the wider community, allowing a larger decentralized democracy.