Update drush to 6.5.0
Puppet 2.7.x is no longer supported

The module_data module is Puppet 3.x only.
Better imports
Stop testing against old version of Puppet 3.x

Weird "uninitialized constant Puppet::DataBinding::LookupError" is
caused when using Puppet < 3.4. Don't know how to fix it and those
tests don't provide a lot of value.