Switch to nanliu-staging from wget

Not all systems have wget...nanliu-staging works around this and is the accepted general-purpose module for this use.

The current nanliu-staging doesn't support strip options, but there is a pull request in at:

https://github.com/nanliu/puppet-staging/pull/30

In the meantime the mhaskel fork of nanliu-staging should be used for its strip support.