Created parameter to build or not from source using mingw

Hi @vijaytripathi, @ppouliot,

This PR contains a new parameter to `nova_dependencies.pp` called `$build_from_source` (better name?) that gets its default value from `params.pp`. My idea is to use this flag as a trigger for the new bits using MinGw.

I've set `false` as its default value until the whole functionality is finished. Let me know if you prefer to keep this value `true` by default or fetch it from hiera (and I'll update the commit).