Refactor screen-connector

Refactor screen-connector

Old version screen connecotor handle UI app and widget
exactly same way. So viewer have to know running app list
to watch other app screen. It's not a good design and make
problems like timing issue. Old design also make troubles
with widgets because it is watching app with appid so,
in multi instance senario sometimes timing issue was occured.

To solve those problems we divide screen connector into two
API sets. For watching UI apps, we provide
screen_connector_watcher* API set.
For widget/watch apps, we provide
screen_connector_toolkit* API set.

Change-Id: Ifdff15e80d36945747fcc37b90a760fc2e5df561
Signed-off-by: Hyunho Kang <hhstark.kang@samsung.com>