Use same version of zfs on centos, as on fedora.

We need this for the new kernel.
Tag spot instances.
Add some tags.
Bump ZFS/SPL version on centos.
Use dotted version.
Use dotted version.
Serve json as json.
Don't mix % and Interpolate.
Improved tagging.
Merge branches 'vagrant-test', 'centos-builder-FLOC-1024' and 'ec2-spot-tags' into staging