snapshot: correctly escape generated xml
snapshot: correctly escape generated xml

Commit 69278878 fixed one direction of arbitrarily-named snapshots,
but not the round trip path.  While auditing domain_conf, I found
a couple other instances that weren't escaping arbitrary strings.

* src/conf/domain_conf.c (virDomainFSDefFormat)
(virDomainGraphicsListenDefFormat, virDomainSnapshotDefFormat):
Escape arbitrary strings.

danwent/libvirt-ovs,VenkatDatta/libvirt,foomango/libvirt,siboulet/libvirt-openvz,nertpinx/libvirt,novel/fbsd-libvirt,jfehlig/libvirt,cbosdo/libvirt,jfehlig/libvirt,jeckersb/libvirt,foomango/libvirt,bjzhang/libvirt,rlaager/libvirt,elmarco/libvirt,usc-isi/libvirt,libvirt/libvirt,warewolf/libvirt,novel/fbsd-libvirt,jfehlig/libvirt,bjzhang/libvirt,soulxu/libvirt-xuhj,dumbbell/libvirt,fabianfreyer/libvirt,olafhering/libvirt,jardasgit/libvirt,warewolf/libvirt,nertpinx/libvirt,shugaoye/libvirt,iam-TJ/libvirt,datto/libvirt,danwent/libvirt-ovs,zhlcindy/libvirt-1.1.4-maintain,elmarco/libvirt,trainstack/libvirt,novel/fbsd-libvirt,jeckersb/libvirt,wiedi/libvirt,bjzhang/libvirt,taget/libvirt,crobinso/libvirt,trainstack/libvirt,emaste/libvirt,VenkatDatta/libvirt,wiedi/libvirt,eskultety/libvirt,wiedi/libvirt,siboulet/libvirt-openvz,usc-isi/libvirt,rmarwaha/libvirt1,iam-TJ/libvirt,leilihh/libvirt,warewolf/libvirt,zhlcindy/libvirt-1.1.4-maintain,rmarwaha/libvirt,jardasgit/libvirt,jeckersb/libvirt,kantai/libvirt-vfork,zippy2/libvirt,nertpinx/libvirt,siboulet/libvirt-openvz,soulxu/libvirt-xuhj,cbosdo/libvirt,soulxu/libvirt-xuhj,rmarwaha/libvirt,taget/libvirt,iam-TJ/libvirt,emaste/libvirt,warewolf/libvirt,kantai/libvirt-vfork,emaste/libvirt,datto/libvirt,warewolf/libvirt,rmarwaha/libvirt1,andreabolognani/libvirt,iam-TJ/libvirt,shugaoye/libvirt,soulxu/libvirt-xuhj,dumbbell/libvirt,dumbbell/libvirt,dumbbell/libvirt,bjzhang/libvirt,VenkatDatta/libvirt,warewolf/libvirt,fabianfreyer/libvirt,zippy2/libvirt,elmarco/libvirt,agx/libvirt,rmarwaha/libvirt,siboulet/libvirt-openvz,taget/libvirt,agx/libvirt,crobinso/libvirt,libvirt/libvirt,zippy2/libvirt,rmarwaha/libvirt1,shugaoye/libvirt,jeckersb/libvirt,datto/libvirt,usc-isi/libvirt,elmarco/libvirt,novel/fbsd-libvirt,jardasgit/libvirt,leilihh/libvirt,datto/libvirt,foomango/libvirt,nertpinx/libvirt,emaste/libvirt,rlaager/libvirt,trainstack/libvirt,eskultety/libvirt,andreabolognani/libvirt,kantai/libvirt-vfork,iam-TJ/libvirt,crobinso/libvirt,novel/fbsd-libvirt,dumbbell/libvirt,jeckersb/libvirt,cbosdo/libvirt,bjzhang/libvirt,rmarwaha/libvirt1,elmarco/libvirt,foomango/libvirt,agx/libvirt,rmarwaha/libvirt1,kantai/libvirt-vfork,zhlcindy/libvirt-1.1.4-maintain,kantai/libvirt-vfork,andreabolognani/libvirt,novel/fbsd-libvirt,rmarwaha/libvirt,fabianfreyer/libvirt,siboulet/libvirt-openvz,usc-isi/libvirt,rlaager/libvirt,rmarwaha/libvirt1,usc-isi/libvirt,rlaager/libvirt,fabianfreyer/libvirt,datto/libvirt,jfehlig/libvirt,zhlcindy/libvirt-1.1.4-maintain,andreabolognani/libvirt,taget/libvirt,leilihh/libvirt,trainstack/libvirt,wiedi/libvirt,leilihh/libvirt,danwent/libvirt-ovs,andreabolognani/libvirt,olafhering/libvirt,rlaager/libvirt,VenkatDatta/libvirt,eskultety/libvirt,novel/fbsd-libvirt,iam-TJ/libvirt,rmarwaha/libvirt,warewolf/libvirt,wiedi/libvirt,danwent/libvirt-ovs,emaste/libvirt,VenkatDatta/libvirt,dumbbell/libvirt,emaste/libvirt,novel/fbsd-libvirt,soulxu/libvirt-xuhj,agx/libvirt,cbosdo/libvirt,crobinso/libvirt,olafhering/libvirt,jeckersb/libvirt,jeckersb/libvirt,zhlcindy/libvirt-1.1.4-maintain,shugaoye/libvirt,trainstack/libvirt,olafhering/libvirt,trainstack/libvirt,fabianfreyer/libvirt,zippy2/libvirt,emaste/libvirt,taget/libvirt,nertpinx/libvirt,eskultety/libvirt,trainstack/libvirt,wiedi/libvirt,cbosdo/libvirt,shugaoye/libvirt,rmarwaha/libvirt,leilihh/libvirt,libvirt/libvirt,jardasgit/libvirt,leilihh/libvirt,eskultety/libvirt,agx/libvirt,foomango/libvirt,libvirt/libvirt,iam-TJ/libvirt,jardasgit/libvirt,danwent/libvirt-ovs,wiedi/libvirt,novel/fbsd-libvirt