Fixed some puppet syntax things.

In init.pp
pkgng_supported and pkgng_version are facts, and need global pathspec $::
The duplicated test for purge_repos_d is unnecessary. Booleans should not be encased in quotes of any kind, so I removed it and added a validate_bool test above

In repo.pp
there is an ensure => $ensure, however $ensure is not a set variable unless it was intended to be a global pathspec var... which I doubt so I have removed it... it will default to ensure => file in this case.
removed per comment