Use notifications for connection registry instead of polling.

Drops roughly 1 second off the start up time of a midlets splash screen.
Looks like this follows the reference implementation:
```java
    jlong time;

    entry->wakeup = alarm;
    time = alarm - (jlong)midp_getCurrentTime();

    if (time >= 0){
        /* if not expired, check timer event */
        entry->state = CHECKED_IN;
        entry->timerHandle = createTimerHandle((int)entry, time);
    } else{
        /* if expired, flag the timer as triggered */
        entry->state = RECEIVED_EVENT;
        entry->timerHandle = 0;
    }
```

and the pushpoll method will then look for any alarms that are RECEIVED_EVENT