Package resource should allow ensure=>">1.0" or ensure=>"<0.10" as well as 'latest', 'installed' and specific version number

It would be helpful if the 'ensure' parameter to the Package resrouce could also specify 'at least version *x' and 'no later than version **y*' as well as 'latest version', 'installed' (IE, any version) or a specific version number.

EG:

    package { 'foo': ensure=>'>1.0' }

would act as 'latest' if the current package was uninstalled or version before 1.0, but would act as 'installed' otherwise. Similarly,

    package { 'foo': ensure=>'<4.0' }

would act as 'installed' if version is <4.0 but would produce an error otherwise.

This would allow us to set a manifest to avoid packages with known problems in a certain version, but not upgrade unless necessary.