Prevent to reset callbacks in InitializeMembers() method

Prevent to reset callbacks in InitializeMembers() method

- Issue:
If client app is terminated and launched again, mmi manager can not send
any output result to client app

- Solution:
Current voice touch engine resets the callbacks in InitializeMembers(),
but this method is invoked by a user utterance for terminating client
app. Thus, resetting callbacks in this situation is not intended result.
This patch removes the logic for resetting the callbacks from the
method. Through this patch, voice touch engine always can send output
result to IU modeule.

Change-Id: I0c7e6c428c077494e6ad12ba38582bec55a501b4
Signed-off-by: Suyeon Hwang <stom.hwang@samsung.com>