packaging: setup: refactoring

Refactored the rpm packaging and setup code for splitting
ovirt-engine-setup in the following packages:

- ovirt-engine-setup
- ovirt-engine-setup-plugin-ovirt-engine
- ovirt-engine-setup-plugin-ovirt-engine-common
- ovirt-engine-setup-plugin-websocket-proxy

Installing ovirt-engine will pull in all of the above
since ovirt-engine is requiring ovirt-engine-websocket-proxy
which now requires ovirt-engine-setup-plugin-websocket-proxy.

Just installing ovirt-engine-setup
will let you to have a working engine-setup and engine-cleanup
wich actually do nothing usefull.

This will ease the migration to otopi for ovirt-dwh and
ovirt-reports and extracting websocket-proxy to its own
package.

Updated dependency on otopi for having nested plugins support.

Change-Id: I572da9cd7b4a2b9e1fdfee4c05e83a0ca31b99bc
Related-To: https://bugzilla.redhat.com/967350
Related-To: https://bugzilla.redhat.com/967351
Related-To: https://bugzilla.redhat.com/967356
Related-To: https://bugzilla.redhat.com/863758
Related-To: https://bugzilla.redhat.com/863757
Related-To: https://bugzilla.redhat.com/985945
Signed-off-by: Sandro Bonazzola <sbonazzo@redhat.com>
Signed-off-by: Alon Bar-Lev <alonbl@redhat.com>