no need to include stdlib
use apt module's update resource
puppet-lint fixes
fix specs to cater for PR #162
fix specs for PR #158
apt modules relies on lsbdistcodename fact
check apt::source in catalog, not the file it creates

We should trust the apt module to do the right thing,
and just test that apt::source is part of the catalogue.
check nginx subclasses are included
add nginx::service spec
add nginx::config spec
add nginx::params spec
add additional cases to nginx::resource::vhost spec