jsonrpc: Moving xml rpc related modules in to rpc package

In order to keep all the modules in single place we move xml rpc module
into the package where old vdsm-api code already resides.

Change-Id: I83246098e084fe15f45d7fe50df6e4ec33d2aaa1
Signed-off-by: pkliczewski <piotr.kliczewski@gmail.com>
Reviewed-on: http://gerrit.ovirt.org/28504
Reviewed-by: Dan Kenigsberg <danken@redhat.com>
Reviewed-by: Nir Soffer <nsoffer@redhat.com>