userportal, webadmin: Guaranteed memory not propagated

Physical Memory Guaranteed parameter (min. allocated memory field) not
propagated to new VM Pool/new VM from VM Template problem fixed.

Current code doesn't store min. allocated memory of the template
to the database and computes it using cluster settings
(max_vds_memory_over_commit).

Now the template min. allocated memory parameter value takes preference
over default expression.

Change-Id: I5b82e01d78de1eca585d6e11d326b0f842db52ae
Signed-off-by: Libor Spevak <lspevak@redhat.com>