Add gaiaflex to Makefile and Dockerfile

[ethanfrey]

Closes #210 (removed wasmgovd)

• Create a new Makefile target build-gaiaflex
• Add it to the Dockerfile
• Allow us to set the enabled proposals via build flags:

-X github.com/CosmWasm/wasmd/app.ProposalsEnabled=true to enable all governance proposals (default all disabled)

-X github.com/CosmWasm/wasmd/app.EnableSpecificProposals=MigrateContract,UpdateAdmin,ClearAdmin to enable some governance proposals

[codecov]

Codecov Report

Merging #229 into master will increase coverage by 0.13%.
The diff coverage is 86.36%.

@@            Coverage Diff             @@
##           master     #229      +/-   ##
==========================================
+ Coverage   72.34%   72.47%   +0.13%     
==========================================
  Files          27       27              
  Lines        2632     2652      +20     
==========================================
+ Hits         1904     1922      +18     
  Misses        616      616              
- Partials      112      114       +2     

Impacted Files	Coverage Δ
app/app.go	88.82% <80.00%> (-0.53%)	⬇️
x/wasm/internal/types/proposal.go	95.21% <91.66%> (+0.26%)	⬆️
x/wasm/internal/keeper/keeper.go	91.15% <0.00%> (-0.54%)	⬇️
lcd_test/helpers.go	75.71% <0.00%> (+0.71%)	⬆️

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[ethanfrey]

@orkunkl you can follow this to see when gaiaflex is in the Dockerfile

[alpe]

👍 changes look good. Very nice to see how configurable the build process became

I did only smoke tests:

• docker build ✅
• gaiaflexd start ✅
• gaiaflex query wasm code list ✅
• home dirs ✅