Cancelled signal is triggered to reset status when gesture is detached.

[Issue#]   N/A
[Problem]  In next case, application can't get ScrollCompleted signal.
           1. Panning scroll view is started.
           2. Call SetScrollSensitive(false)
               to stop movement of scroll view and pick the object inside.
           3. Scroll view doesn't trigger Scrollcompleted signal
               until SetScrollSensitive(true) is called.
[Cause]    Scroll view is still thinking it's still being animated
            even though it's stopped and its sensitive is false.
[Solution] Cancelled signal is triggered to reset status when gesture is detached.

Change-Id: I7a03bd335072593bdad528be498f5f1acbfb9c1f
Signed-off-by: David Steele <david.steele@partner.samsung.com>