Full re-sync should run as a periodic job

[lunkwill42]

nav-argus-glue only performs a full sync at startup (or specifically when called with a command line option). After the full sync, the glue service only sends event changes as they come in from the event engine.

However, NAV and Argus will sometimes still get out of sync, in at least two different scenarios:

1. Sometimes, a request to Argus may fail, and there is currently no retry mechanism. The update will get lost.
2. When a user closes a NAV alert through the UI, there is actually no closing event sent processed by the event engine (the alerthist database entry is modified directly). This type of closing-action will not trigger the glue service to update Argus.

If the full sync operation were run periodically while navargus is waiting for events, these issues could be mitigated.