GH-130 Fix overwrite of user config data

[reidmv]

Users may have their own config data specified for the PE Master group.
This commit ensures that when peadm enforces node group configuration
including config data on the PE Master group, it merges required config
into existing user data to avoid configuration loss.

Fixes #130

[puppet-community-rangefinder]

peadm::merge_ng_config_data is a function

that may have no external impact to Forge modules.

peadm::setup::node_manager is a class

that may have no external impact to Forge modules.

This module is declared in 0 of 575 indexed public Puppetfiles.

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Exact matches are those that we can positively identify via namespace and the declaring modules' metadata. Non-namespaced items, such as Puppet 3.x functions, will always be reported as near matches only.