Add md5sums to installer

md5sums is included with installer as:
1. Very small.
2. A corrupt download of md5sums can cause the installer to fail or
fail to detect invalid assets
Check in fs_homepath for assets

Check for assets in fs_homepath as well as fs_basepath. This is useful
as maps are downloaded to fs_homepath when connecting to a game server.
Add information about forums

Not sure how to make it a link (is it even possible?).