Create NSIS windows installer binary

[nhorman]

Write a windows binary installer using open source NSIS tool and commit to a new installer repository:

Tasks

Beta Give feedback

1. Installer should hold both 32 and 64 bit openssl binaries
2. Installer should allows installation target to be selected
3. Installer should present user with Apache license to accept
4. Installer should create registry keys to record per-installation location of default paths that are set at build time in non-windows openssl binaries
5. Installer should write uninstaller to install path

[nhorman]

I've moved the windows installer PR to be part of the installer repo