Enforce that npm is installed with collectors before using it

[carlossg]

A package with provider => npm may run before npm is installed and fail

Not sure if it is ok to add it in the module, but at least should be in the README

if $::operatingsystem != 'ubuntu' {
Package['npm'] -> Package <| provider == npm |>
} else {
Package['nodejs'] -> Package <| provider == npm |>
}

An nodejs::npm anchor would also simplify the rule above

Does it look reasonable?

[jamescarr]

👍 this really caused me some headaches today!

[Twipped]

This looks to be the source of #57

Edit: Confirmed, added the above code to line 83 of init.pp and my dependency issue went away.

[juniorsysadmin]

Should no longer be occurring. Note that we also use require => Class['nodejs'] in the npm defined type.