Mods

two changes: 
  1. php::cli is also optional now
  2. changed param lookup mechanism

The background for the 2nd change is that (at least on our systems, puppet 3.4.2 with hiera 1.3.1) `hiera_hash('my_lookup', {})` always fails if the key cannot be found in hiera. `hiera('my_lookup', false)` works, though.