Reset memory pool when core terminate

Reset memory pool when core terminate

Since we can create new Core without process terminate, (e.g. offscreen application)
We should ensurely clear the memory usage.

Without this clean-up process, some memory might be remained after
core terminate. For example, some OwnerPointer<Node> are exist at Message during
app terminate, it might not be release surely.

Change-Id: Iaef0b16bcd6631aa8a52e9b52bfa39374be770b6
Signed-off-by: Eunki, Hong <eunkiki.hong@samsung.com>