man: updated bcfg2-admin man page
man: Removed old plugins from bcfg2.conf man page
Rewrote SSLCA as Cfg handler.

This adds encryption support to SSL key creation (much like SSH
private keys), and the ability to generate keys and certs that are
specific to groups, instead of just to hosts.  It also moves the SSLCA
data (the XML files describing keys and certs as well as the keys and
certs themselves) into the Cfg tree, rather than off in their own
separate place.

tools/upgrade/1.4/migrate_sslca.py can be used to migrate to the new
format.

This also adds XMLCfgCreator, a CfgCreator that makes it easier to
create data based on XML descriptions of it (which is exactly what the
SSH key and SSL CA creators do), including built-in support for host-
and group-specific data, encryption, and so on.