(maint) Add autoconf to SLES mock stubs

BuildRequires are apparently sort-of unreliable on SLES which is
causing the HTTPD package to disregard them when building HTTPD.
Subsequently, autoconf doesn't get installed so the build fails.
This adds in the troublesome package, which will probably be of
benefit somewhere up the road.

This commit also alphabetizes the packages installed into the
SLES mock stubs.
(maint) Re-enable ccache plugin for mock stubs

We'd previously disabled these while working through an issue,
but we forgot to re-enable them. This commit re-enables the plugin.
Merge pull request #84 from mckern/master

(maint) Add autoconf to SLES mocks, and re-enable ccache in mock stubs