Release Candidate Xen 3.4.1

From Keir on xen-devel:

The first release candidate for Xen 3.4.1 is tagged as 3.4.1-rc1 at http://xenbits.xensource.com/xen-3.4-testing.hg

Quite a few important fixes have been made since 3.4.0. Please test and let’s get this one out quickly!