Set service state by engine launching status

Set service state by engine launching status

- Issue:
If the client is out of service by service reset, client can not get
proper service state.

- Solution:
By the on-demand reprepare logic, the clients subscribing service state
changed event can not get service state until that the client invokes
the API. However, if the client invokes the API depending on service
state, the client may not call the API, so it can be out of service
permanently.
To solve this problem, this patch adds logic for checking engine
launching status. Through this patch, the client library can check
whether the engine is launched or not. When the engine is launched, the
client library notifies the service state changed event to the client
app can run the code which depends on the service state.

Change-Id: If4e3310054143732f5705ed4acfae42762fa21b1
Signed-off-by: Suyeon Hwang <stom.hwang@samsung.com>