Fix genesis functionality after F1 adoption

[hallazzang]

Description

closes: #104

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[codecov]

Codecov Report

Merging #112 (1e7124f) into master (9d7cd9c) will increase coverage by 0.34%.
The diff coverage is 82.39%.

@@            Coverage Diff             @@
##           master     #112      +/-   ##
==========================================
+ Coverage   66.01%   66.36%   +0.34%     
==========================================
  Files          24       24              
  Lines        2107     2224     +117     
==========================================
+ Hits         1391     1476      +85     
- Misses        580      608      +28     
- Partials      136      140       +4     

Impacted Files	Coverage Δ
x/farming/abci.go	0.00% <0.00%> (ø)
x/farming/types/keys.go	0.00% <0.00%> (ø)
x/farming/keeper/genesis.go	79.46% <84.09%> (+3.14%)	⬆️
x/farming/keeper/reward.go	88.26% <86.20%> (+0.68%)	⬆️
x/farming/keeper/staking.go	90.90% <90.00%> (+0.43%)	⬆️
x/farming/types/genesis.go	52.63% <100.00%> (+3.50%)	⬆️
x/farming/types/msgs.go	68.42% <0.00%> (-7.07%)	⬇️
x/farming/keeper/keeper.go	75.00% <0.00%> (-2.78%)	⬇️

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[hallazzang]

It still needs more test codes

[dongsam]

Could you check this comment #115 (review) and apply also this issue and PR? and need to resolve some conflicts