[Swan-dev] Sahana's RSA-PSS code merged in - upgrade strongswan to 5.6.3

[Paul Wouters]

I've merged in Sahana's RSA-PSS code, which requires strongswan 5.6.3.
This means that if you don't upgrade the guests to this, the strongswan
tests will fail in swan-prep since it refuses to run the test (to avoid
people pingponging output when they have different strongswan versions)

For fedora-22 I've made the rpm available at:

https://ftp.nohats.ca/strongswan/strongswan-5.6.3-1.fc22.x86_64.rpm

For f28, it should come with that version automatically.

Paul