core: Fill and check arch when importing VM and Template

* On importing VM and Template, its architecture must match with
  cluster architecture, otherwise an error must be displayed. It's
  being checked in the import command for each one.
* On importing OVF files, the same validation is necessary, and filling
  the architecture for VM and Template is necessary. The architecture
  is filled based on the OS architecture, otherwise the architecture
  will be undefined.
* If VM or Template has undefined architecture, it cannot be imported,
  so a error message is displayed when trying to import it.

Change-Id: I6ac6093e253225f801e216310828a7afba73f9e6
Signed-off-by: Leonardo Bianconi <leonardo.bianconi@eldorado.org.br>
Signed-off-by: Vitor de Lima <vitor.lima@eldorado.org.br>
Signed-off-by: Gustavo Pedrosa <gustavo.pedrosa@eldorado.org.br>