Problem: (CRO-455) Byzantine validators are not slashed

[devashishdxt]

Solution: Add byzantine validators to slashing queue and slash them when wait time passes

[tomtau]

looks good, just one small style improvement -- clippy already warned about it in store_valid_genesis_state, so could be good to refactor it.

• the punishment would ideally be proportional to the number of failing validators -- if that's a bit complex to do now, we can postpone from this PR, sketch out it first in https://github.com/crypto-com/chain-docs and later fix it.

[tomtau]

@devashishdxt init config is currently feature-guarded, as it's not needed in tx-validation enclave etc., so compiling enclaves fails due to this:

error[E0432]: unresolved import `crate::init::config`
614	 --> /tmp/drone-6NS9G1rMvn8mGTkF/drone/src/chain-core/src/init/coin.rs:6:18
615	  |
616	6 | use crate::init::config::SlashRatio;
617	  |                  ^^^^^^ could not find `config` in `init`
618	
619	
620	error[E0432]: unresolved import `crate::init::config`
621	 --> /tmp/drone-6NS9G1rMvn8mGTkF/drone/src/chain-core/src/state/account.rs:4:18
622	  |
623	4 | use crate::init::config::SlashRatio;
624	  |                  ^^^^^^ could not find `config` in `init`
625	
626	
627	error: aborting due to 2 previous errors
628	
629	For more information about this error, try `rustc --explain E0432`.
630	error:

SlashRatio could either be moved out to a separate module, or its uses in Coin and StakedState can be feature guarded (if it can be done -- for StakedState, it may not)

[codecov]

Codecov Report

Merging #495 into master will increase coverage by 0.39%.
The diff coverage is 94.02%.

@@            Coverage Diff            @@
##           master    #495      +/-   ##
=========================================
+ Coverage   65.71%   66.1%   +0.39%     
=========================================
  Files         117     120       +3     
  Lines       13602   13794     +192     
=========================================
+ Hits         8938    9118     +180     
- Misses       4664    4676      +12

Impacted Files	Coverage Δ
chain-abci/src/main.rs	2.63% <ø> (ø)	⬆️
chain-abci/src/lib.rs	100% <ø> (ø)	⬆️
chain-core/src/init/config.rs	68.65% <100%> (+0.47%)	⬆️
chain-core/src/state/account.rs	75.21% <100%> (+0.86%)	⬆️
chain-core/src/init/coin.rs	88.51% <100%> (+0.69%)	⬆️
chain-abci/src/slashing.rs	61.11% <61.11%> (ø)
chain-abci/src/punishment.rs	85.71% <85.71%> (ø)
chain-abci/src/app/app_init.rs	69.66% <87.5%> (-0.04%)	⬇️
chain-abci/src/app/mod.rs	82.45% <91.66%> (+0.26%)	⬆️
chain-abci/src/app/slash_accounts.rs	96.77% <96.77%> (ø)
... and 4 more

[tomtau]

bors r+

[bors]

Build succeeded

• continuous-integration/drone/push
• continuous-integration/travis-ci/push