Connect synchronously when app uses setting API

Connect synchronously when app uses setting API

- Issue:
The setting API did not connect to vc server.

- Solution:
When setting API is invoked, the setting library invokes request hello
function only once. However, the request hello function uses
asynchronous connect and setting library did not waiting it. Thus,
setting API always fails to connect to vc server.
This patch changes connection function to synchronous one. Through this
patch, setting API can connect vc server properly.

Change-Id: I961dd545d2e92f0a4d644742e8b747086bd00e75
Signed-off-by: Suyeon Hwang <stom.hwang@samsung.com>