(maint) Adding missing doc comments for regex adapter.

Adding missing doc comments to make doxygen happy.
(maint) Prevent loading of ruby if --no-custom-facts is specified.

If the --no-custom-facts option is given to cfacter, don't bother loading Ruby.
(CFACT-46) Implement aggregate resolutions in Ruby API.

Implementing Facter::Core::Aggregate with chunk and aggregate methods.

This allows for aggregate resolution types and conforms to Ruby Facter's
implementation of defaulting to a deep-merge of chunks.