Allow for custom content

[Falkor]

Add a new parameter custom_content to allow for quickly test and deploy directives within slurm.conf not yet managed as [hiera] parameters of the module... I should have planned that from the beginning ;)

[Falkor]

Example of hiera setting (multiline YAML with |) (used in tests/vagrant/puppet/hieradata/custom.yaml):

slurm::custom_content: |
  SlurmctldSyslogDebug=fatal
  SuspendExcNodes=iris-[10-20]:4,iris-[80-90]:2

Which results in the following:

$> vagrant provision --provision-with puppet slurm-master
==> generating hieradata/locals.yaml
==> slurm-master: Running provisioner: puppet...
[...]
==> slurm-master: Info: Applying configuration version '1549121528'
==> slurm-master: Notice: /Stage[main]/Slurm::Config/File[slurm.conf]/content:
==> slurm-master: --- /etc/slurm/slurm.conf	2019-02-02 15:03:56.557671308 +0000
==> slurm-master: +++ /tmp/puppet-file20190202-24821-1nhsutc	2019-02-02 15:32:16.838333212 +0000
==> slurm-master: @@ -245,6 +245,11 @@
==> slurm-master:  MpiDefault=pmi2
==> slurm-master:  MpiParams=ports=55000-59999
==> slurm-master:
==> slurm-master: +### Custom content
==> slurm-master: +SlurmctldSyslogDebug=fatal
==> slurm-master: +SuspendExcNodes=iris-[10-20]:4,iris-[80-90]:2
==> slurm-master: +
==> slurm-master: +
==> slurm-master:  ###############################
==> slurm-master:  ### Network Characteristics ###
==> slurm-master:  ###############################
==> slurm-master:
==> slurm-master: Info: Computing checksum on file /etc/slurm/slurm.conf
[...]