Show RPKI BGP origin validation

[mrplow87]

Because of the rise of RPKI validation among network operators, I thought it would be nice to show a route's validity state in BIRD-LG.
So I've added an API call to RIPE NCC's RPKI Validator (Example API URL) calls to lg.py to show BGP origin validation states when displaying routes.

If there's interest for this to be in here, I'll create a pull request with my changes. It's not beautiful (code and output), so any hints to make it better are welcome. I'm fairly new to Python, so please be gentle.

So far, the API URL is hard coded and it's an external resource. But it could be changed to be configurable, so a local instance of the validator software can be accessed.