Don't fetch localkube when version specified is default

[r2d4]

Instead, use the binary that is already bundled with go-bindata.

ref #1687

[codecov-io]

Codecov Report

Merging #1688 into master will decrease coverage by 0.03%.
The diff coverage is 100%.

@@            Coverage Diff             @@
##           master    #1688      +/-   ##
==========================================
- Coverage   38.77%   38.73%   -0.04%     
==========================================
  Files          51       51              
  Lines        2664     2664              
==========================================
- Hits         1033     1032       -1     
  Misses       1452     1452              
- Partials      179      180       +1

Impacted Files	Coverage Δ
pkg/minikube/cluster/cluster.go	44.54% <100%> (ø)	⬆️
pkg/util/kubeconfig/config.go	51.4% <0%> (-0.94%)	⬇️

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[medyagh]

thanks looks good