core: Confusing message fix

Changed the message related to ACTION_TYPE_FAILED_VM_STATUS_ILLEGAL in
all of the files.

Change-Id: Ie481d2ece9a330e33051ae231491874edd25de31
Bug-Url: https://bugzilla.redhat.com/1091685
Signed-off-by: Idan Shaby <ishaby@redhat.com>