fix missing dependency on augeas

make sure that the augeas class has been applied before attempting to do any
augeas operations. without this, you will non-deterministically get:

    err: /Stage[main]/Shorewall::Base/Augeas[shorewall_module_config_path]: Could not evaluate: Save failed with return code false
augeas definition needs to make sure the shorewall package is installed before it tries to run
add requirement for augeas module
change the 'include augeas' to a 'require augeas'
remove the class requirement in the augeas block, it is handled by the top-level require