core: auto generate Handler fields from annotations

Use annotated fields to generate what fields can be edited and
on which status.

Introduced 2 annotations;

 @EditableField
 private String name;

 @EditableOnVmStatus(status = Down)
 private Guid vdsGroupId;

note: several field names have bean updated to comply to java property
convention.

Signed-off-by: Roy Golan <rgolan@redhat.com>
Change-Id: I8441f030c161c99c630a945b8b0228114665aa17