Unable to limit virtual machine's memory and CPU cores when build

I'm trying to build the latest J2V8 from source because I can't find any pre-built binary of the latest version. (The latest version in Maven Central repository is v4.6.0 with Node.js version v5.9.0, which is a definitely out-dated version for me.)

So I followed the instructions in BUILDING.md and tried to build J2V8 with the build-configuration `windows-x64 @ Vagrant` (I have Vagrant and Oracle VM VirtualBox installed already) but the building process always gets my computer stuck. What I've found is that the build system setting the configuration of the virtual machine to 8 GB of memory and 4 CPU cores every time but the host machine has exactly as much as 8 GB of memory and 2 physical CPU cores. That may be the reason for my problem.

Sadly, I'm not familiar with Vagrant and your build system, I don't find any configuration file responsible for this. Any solution or workaround? Thanks.

Start with BUILDING.md and the `windows-x64 @ Vagrant` build configuration, then trace where the virtual machine receives its memory and CPU settings. Confirm whether those values can be configured for a host with 8 GB of memory and 2 CPU cores; done means the build no longer requires excessive fixed resources.

Written by the indexing model from the issue text.