Rackspace plugin rescues Errno::ENOENT if xenstore-* utils are not found
Remove Ohai::Exceptions::Exec (not thrown by shell_out) in Rackspace plugin
Rackspace Plugin: Remove remaining Ohai::Exceptions::Exec and don't use exceptions for flow control
Merge pull request #342 from jcsalterego/fix-rackspace-plugin-rescues-errno-enoent

OHAI-587: Rackspace plugin rescues Errno::ENOENT if xenstore-* utils are not found