Too much staking logic in app-simulation/genesis initialization

[rigelrozanski]

During my investigation of simulation bugs due in introducing the distirbution module I realized the logic flow for staking is disembodied. A series of important hooks have recently been introduced into staking however, these hooks are not being properly called from the application, BECAUSE the application is actually performing some of the core staking logic for initialization. There needs to be a much clearer separation of concerns between staking and the app - there is a decent amount of code contained within:

cmd/gaia/app/sim_test.go
cmd/gaia/app/genesis.go 

should really be refactored from the app into staking, I noticed that some of what's happening in the app is actually duplicated code from staking! Anyways yeah this should be restored, so as new hooks and core functionality is expanded in staking, the app can take advantage by default rather than needing to have code updates itself

[cwgoes]

Ref #2452 (comment).

[rigelrozanski]

dependant on #3006

[rigelrozanski]

closed by #4159