issue #75: Validate parameters when updating a Template

While editing a Template we need to make sure:
     - the template name has at least one character
     - the value specified to memory must be a number
     - the value specified to cpus must be a number

Signed-off-by: Aline Manera <alinefm@br.ibm.com>
tests: Add tests to verify data validation when editing a template

While editing a template verify if template name has at least one character; the
value specified to memory is a number; the value specified to cpus is a number

Signed-off-by: Aline Manera <alinefm@br.ibm.com>