Improve package script

* Friendly OS name for packaged zips
* Options to skip test and toolchain building
* Fix problems running on Windows

Unfortunately we can't build 64bit and 32 bit Windows binary 64bit. Seeing issues like [this](https://github.com/mitchellh/gox/issues/19#issuecomment-68117016). A solution is to build 64bit hub on a 64bit machine and 32bit hub on a 32bit machine. It's annoying but get us unblock for now.