Switch to source-build OpenSSL on Windows platforms

[djp952]

Given the short runway, I opted to prebuild OpenSSL for Windows and UWP, but I hate doing that. Given how Visual C++ runtimes work and that libcurl and libz are source built on Windows, it's the better option.

The library files for Windows platforms are also massive and makes cloning the dependency repo painful, but that's a lesser concern.

[djp952]

Not doing this; switching to wolfSSL instead (#110). It's a far easier platform to work with.