core: RngDeviceCommand fixes

the class is a conctrete class,
No reason for its CTORs not to be public

Change-Id: Ie789c93d918274370aa1007ff838f3d0071b1b60
Signed-off-by: Yair Zaslavsky <yzaslavs@redhat.com>
core: Adding context ctor ProcessOvfUpdateForStorageDomain

Change-Id: Ia170d17191b3fd541fa4b0d695a94e3ed06dee72
Signed-off-by: Yair Zaslavsky <yzaslavs@redhat.com>