Dev command should run build script instead of transpiling data sources

@jlengstorf commented on [Sat Dec 23 2017](https://github.com/gramps-graphql/data-source-base/issues/16)



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@kbrandwijk commented on [Sat Dec 23 2017](https://github.com/gramps-graphql/data-source-base/issues/16#issuecomment-353705473)

Should probably go here: https://github.com/gramps-graphql/gramps-cli?

