Make sysinfo into a runner Plugin.

Make sysinfo into a runner Plugin,
rename application from AvocadoRunnerApp to AvocadoApp,
due all options are now implemented as plugins and
Avocado is now a core application.

Signed-off-by: Ruda Moura <rmoura@redhat.com>
Merge pull request #2 from ruda/moreplugins

Make sysinfo into a runner Plugin.