Add upgrade recipe.  To use it supply eucalyptus and euca2ools repo to upgrade to.
example upgrade.json:

{
    "eucalyptus": {
      "yum-options": "--nogpg",
      "eucalyptus-repo": "http://packages.release.eucalyptus-systems.com/yum/builds/eucalyptus/branch/maint-3.4-testing/centos/6/x86_64/",
      "euca2ools-repo": "http://packages.release.eucalyptus-systems.com/yum/builds/euca2ools/commit/fd0d10fd240dd04616bdc303b71687dda673bc71-2014-01-23-001/centos/6/x86_64/"
    },
    "run_list": [
    	"recipe[eucalyptus::upgrade]"
    ]
}

This change also moves from using exec command to stop/start services to use chef's service API