Create new proxy handle when engine is changed

Create new proxy handle when engine is changed

When engine is changed or mode is changed, client has to make new proxy handle to change stub
app ID.
Previous code creates new proxy handle only when mode is changed. So, if engine is changed,
previous code does not connect new engine but the engine before changed.

This patch makes the client creates new proxy handle not only when mode is changed, but also
engine is changed. For checking engine change, information structure stores engine app id of
current proxy handle.

Change-Id: Ie59a18a4cbdc0862e636d326715b95d25a694003
Signed-off-by: Suyeon Hwang <stom.hwang@samsung.com>