[BB10] Fix: Don't set a reminder when adding to calendar.

It appears that when creating a new CalendarEvent object on BlackBerry 10
its reminder is set to "At Start" instead of "No Reminder".
[SYM, BB10] Delay starting search one second after user stops typing.

On Harmattan it looks like onTextChanged signal is fired only after a
whole word/space was typed in. But nn Symbian and BlackBerry it's fired
after each letter was typed. So, not to flood a server with search
requests, we're only starting a search one second after user stops
tpying/deleting the text.
Also start search when Return/Enter is pressed.

Don't start search when input text is empty.