Set bech32 prefix

[alpe]

Resolves #313

• Default "wasm" in app
• Set prefix in build (not really needed with app default but consistent with building other artifacts)

No covered are cosmos prefixes in unit tests

[codecov]

Codecov Report

Merging #316 (6045693) into master (06cd063) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##           master     #316   +/-   ##
=======================================
  Coverage   17.53%   17.53%           
=======================================
  Files          35       35           
  Lines       10519    10519           
=======================================
  Hits         1844     1844           
  Misses       8572     8572           
  Partials      103      103           

Impacted Files	Coverage Δ
app/app.go	88.38% <ø> (ø)

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[webmaster128]

thanks