Simulation improvements (logging fix, random genesis parameters) (#2617)

* Print out initial update on every block
* Randomize simulation parameters
* Randomize initial liveness weightings
* Randomize genesis parameters
* fixed power store invariant
* IterateValidatorsBonded -> IterateBondedValidatorsByPower
* WriteValidators uses IterateLastValidators rather than IterateBondedValidatorsByPower
* fixed democoin interface

Closes #2556
Closes #2396

Via #2671:
closes #2669
closes #2670
closes #2620

Offshoot issues:
#2618
#2619
#2620
#2661

baseapp/baseapp.go

@@ -394,6 +394,7 @@ func handleQueryCustom(app *BaseApp, path []string, req abci.RequestQuery) (res
 
 	ctx := sdk.NewContext(app.cms.CacheMultiStore(), app.checkState.ctx.BlockHeader(), true, app.Logger).
 		WithMinimumFees(app.minimumFees)
+
 	// Passes the rest of the path as an argument to the querier.
 	// For example, in the path "custom/gov/proposal/test", the gov querier gets []string{"proposal", "test"} as the path
 	resBytes, err := querier(ctx, path[2:], req)