Applications cache with time to live

The loopback component push stores the application data in the cache when sending notifications. The cache is never emptied or updated, so if the application data changes, the changes will not take effect.
This can be solved by periodically emptying the cache.

Added 2 settings:
stdTTL : standard time to live in seconds
checkPeriod: check period in seconds which deletes cache, default is 0, which never deletes