Allow customization of partition parameters through a hash in the hieradata

[mboisson]

This is to allow to define things such as Maxtime for partitions.

[mboisson]

Note that config_addendum is not suitable for this purpose, because

Default values can be specified with a record in which PartitionName is "DEFAULT". The default entry values will apply only to lines following it in the configuration file and the default values

which means any settings done for the DEFAULT partition would not apply to partitions defined earlier in the configuration file.