Add RASP Sources

[lordfolken]

http://rasp.inn.leedsmet.ac.uk/XCSoar/ lists a Downloadable rasp source. A current limitation of this is that XCSoar expects the RASP file to be named xcsoar-rasp.dat. So only one file can currently exist at the time.

[r0w4n]

@lordfolken this link is dead. I recognise that the uk doesn't have a rasp source in xcsoar. What can be done? Do we need to source a feed?

[lordfolken]

What needs to be done:

• add rasp sources to this repository
• remove them from hard coded source in xcsoar
• teach xcsoar to get the rasp sources from the repo

[lordfolken]

See: https://github.com/XCSoar/XCSoar/blob/master/src/Weather/Rasp/Providers.cpp