feat(lib/grandpa): init polite grandpa impl

[jimjbrettj]

Changes

• Create a file reputation.go (lib/grandpa) that defines how cost/benefits and cost calculation functions will be implemented. This is in comment form for now, as I am just looking to get the approach approved. Comments will be converted to code when implementation begins.
• Create a README for polite grandpa

Tests

none

Issues

#2861

Primary Reviewer

@EclesioMeloJunior

[codecov[bot]]

Codecov Report

Merging #2860 (ba8be5c) into development (b2f2ab1) will increase coverage by 0.19%. The diff coverage is n/a.

Additional details and impacted files

@@               Coverage Diff               @@
##           development    #2860      +/-   ##
===============================================
+ Coverage        63.05%   63.24%   +0.19%     
===============================================
  Files              217      218       +1     
  Lines            27164    27196      +32     
===============================================
+ Hits             17128    17201      +73     
+ Misses            8459     8416      -43     
- Partials          1577     1579       +2     

[EclesioMeloJunior]

Looks good. I am guessing this will get integrated with peer reputation logic in dot/peerset, in order to disconnect or ban peers, right? I think first step would be to connect grandpa service to peer reputation logic to send reputation change, say using channels.

Yes, but right now before starting the integration between peerset <-> grandpa we're identifying the politeness rules, punishment values and once we have these rules we can start applying them in the right places

[jimjbrettj]

This is being closed due to the large refactor happening to grandpa