symlink all distros facets to a common set of 'supported' targets

This makes it easier to maintain the supported/tested targets.

Signed-off-by: Sage Weil <sage@inktank.com>
distros: test rhel/centos 6.5 instead of 6.4
distros: add 14.04 to supported list

Signed-off-by: Sage Weil <sage@inktank.com>
Merge pull request #20 from ceph/wip-distros

symlink all distros facets to a common set of 'supported' targets