Deprecate OpenSSL

Attn: @dirk

See e.g.: https://github.com/dirk/OpenSSL.jl/issues/3, http://pkg.julialang.org/?pkg=OpenSSL&ver=0.2

It seems like a package for something "important" like OpenSSL should, well, work, but it looks like this package got merged with only 1 actual commit and was never touched again. I'd actually be in favour of completely removing the package but I'm not sure if that can break something.