installing virtualenv broken in master

[jantman]

The python class [says|https://github.com/stankevich/puppet-python/blob/master/manifests/init.pp#L33] that the "virtualenv" parameter should be a string, 'absent|present|latest' and validates this (twice in fact). However, the install class still expects a boolean. The end result is that

class {'python':
  virtualenv => 'present',
}

actually ensures absent.

[jantman]

This was in error... sorry.