OpenSSL.jl ignores JULIA_SSL_CA_ROOTS_PATH

[mortenpi]

It seems that OpenSSL.jl doesn't honor JULIA_SSL_CA_ROOTS_PATH, which means that if you're using HTTP.jl with the default backend, the requests will fail against servers using custom certifications with OpenSSL.OpenSSLError("unable to get local issuer certificate").

Would it make sense to depend on https://github.com/JuliaLang/NetworkOptions.jl to pick up the path, and pass ca_roots_path() on the the OpenSSL library? I assume there's some way to configure the CA path.