Actor wait() method

This method is stopping javascript execution until all actor methods
return

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jollamobile.com>
Actor.reload(), unified js ffi

Actor.reload() forcibly reloads actor module from the same source.

Actor implementation got execute() function to wrap c++ code for
converting c++ exception into js exception in unified way

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jollamobile.com>
[cutes] API enchanced, actor sync. Fixes: JB#5164

Signed-off-by: Denis Zalevskiy <denis.zalevskiy@jollamobile.com>