Change self-signed certificate RSA key size from 4096 to 2048 bits

RPM installation time should improve by quite a bit, especially on
systems with bad entropy source. Really, why spend 100x more time to
generate 4096 bits, when 2048 bits is perfectly fine by today's
standards, let alone that we're talking about a self-signed certificate.
Upgrade openssl to 0.9.8zc.

Also refactored the RPM spec file a bit, to only mention the version in
one place.
Further sanitisation of the self-signed certificate

Added "-sha256 -utf8" to work in future browsers, removed unneeded stuff
from subject since CN is the only thing that matters in self-signed
certificates.
Merge pull request #24 from jimis/master

OpenSSL version update, and self-signed cert generation.