ecore_cocoa: use a timer instead of a poller to be more responsive when dealing with...

ecore_cocoa: use a timer instead of a poller to be more responsive when dealing with cocoa Event.

As all Mouse and Keyboard events comme from Cocoa, the poll period must
be reduced. Backwards of this method is that when no signal are
received for a long period, the timer fired anyway and consumes CPU
for nothig but it seems there is no easy method to integrate NSApplication
mainloop into an existing one.

Signed-off-by: Cedric BAIL <cedric@osg.samsung.com>