build (buffalo build) failing fixes #1323

[markbates]

This ensures that build time packages are installed by either running go get or dep ensure right before the binary is built in buffalo build.

[codecov]

Codecov Report

Merging #1331 into development will decrease coverage by 0.13%.
The diff coverage is 0%.

@@               Coverage Diff               @@
##           development    #1331      +/-   ##
===============================================
- Coverage        48.28%   48.15%   -0.14%     
===============================================
  Files               90       91       +1     
  Lines             3991     4002      +11     
===============================================
  Hits              1927     1927              
- Misses            1962     1973      +11     
  Partials           102      102

Impacted Files	Coverage Δ
buffalo/cmd/build/deps.go	0% <0%> (ø)
buffalo/cmd/build/builder.go	0% <0%> (ø)	⬆️

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