Use Easy-RSA 2.2.2 instead of the master branch with Debian Jessie and Ubuntu Saucy

This was needed for Debian Jessie, but using always the latest Easy-RSA
was a bad idea.

I will force Easy-RSA 2.2.2 for now and until Jessie becomes stable.
Then we can probably just use the distro packages instead of Github,
but for now this will work.