add nice api client wrapper for `junos-ez-stdlib`
add nice api client wrapper for `junos-ez-stdlib`

The main purpose of this class is to hide any gnarly details of making
requests to the Junos XML API using the `junos-ez-stdlib` Ruby client.
We want provider code to be clean and easy to follow.

opscode-cookbooks/netdev,chef-partners/netdev,Juniper/netdev,chef-cookbooks/netdev