The source for the go version is located at cli/ubi.go, and can be
compiled with `rake ubi`, with the resulting binary created at
cli/ubi
It passes all cli specs:
```
UBI_CMD=./cli/ubi rspec spec/cli_spec.rb
...
Finished in 0.07275 seconds (files took 0.44337 seconds to load)
21 examples, 0 failures
```
It's much faster than the ruby version, mostly do to ruby startup:
```
rspec spec/cli_spec.rb
...
Finished in 3.33 seconds (files took 0.44545 seconds to load)
21 examples, 0 failures
```
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