This seems like a repeat of a question in,
I think the core point here is that a lot changed about how package development works between Julia v0.6 and Julia v1.0. You might start by reviewing those changes. For example,
http://abelsiqueira.github.io/blog/package-development-on-julia-10/
It’s fairly similar to how it use to work, just make sure that you are working out of the “dev” directory and that your active environment is setup to use that version of the code.