Add warning comment to getinfo

Warn that people should not add new information, or change current
information returned by getinfo.
Remove hopelessly outdated build-msw.md

Anyone building bitcoind/-qt on windows is welcome to contribute
a new one. The current information in this document is outdated,
or otherwise mostly worthless.
contrib: remove getwork-based pyminer

As the `getwork` API doesn't exist anymore, currently this script is useless.

It would be nice to have a `getblocktemplate`-based Python example of a
miner, but there is no point in keeping this one around except to
confuse people.
Avoid querying DNS seeds, if we have open connections.

The goal is to increase independence and privacy.
Merge pull request #4559

2e7009d Avoid querying DNS seeds, if we have open connections. (Jeff Garzik)
Update openssl.org URL to include https://

Suggested by whitj00.  Fixes #4595
Merge branch '2014_07_remove_pyminer' of git://github.com/laanwj/bitcoin into merge-pyminer