Complete the transition to puppet-strings

228a537 introduced regressions. This
fixes them.

Fix typo in type

Drop support for Redis 2, Debian 8 and Ubuntu 14.04; add Debian 9 and Ubuntu 18.04

* Add feature to use instances in hiera

* revert

* try again

* Missing this

* remove whitespace

* Add Hash

* replace with each

* add arguments

* insert values into loop iteration

* mis-aligned

* soft tabs

* remove comment - not relevant to all

* Update hash type

* Add comment/notes

* Add short description ::instances

This sets data types for most parameters that previously had none. It
also moves static defaults from params.pp to inline. While this
duplicates a few between Redis and the sentinel, the user would already
need to know these were linked. The benefit is a much more readable
reference documentation.

Stricter data types

502ff38 tightened the data types, but
there's no reason to only allow unprivileged ports.

502ff38 tightened the data types, but
too much. It's valid not to bind on a unix socket and the template
allowed this.

Allow privileged ports in data types

This treats the entire Red Hat OS family equal.

For apt handling the before is cleaned up since the apt::update
dependency is defined within apt::source and apt::ppa while the package
is handled because init.pp does preinstall before install.

Clean up preinstall handling and use modern facts

This splits the parameters into groups (roughly) matching preinstall,
init and sentinel.

This should match what's in EPEL, Debian and Ubuntu.

Closer match parameter to OS defaults

Allow empty unixsocket(perm)

On Red Hat the software collections allow for multiple versions. On RHEL
this is also supported for customers where EPEL is unsupported.

To implement this, the globals pattern is implemented giving users an
easy way to select the SCL at a global level. Acceptance tests are added
to ensure it works.

For convenience, it can ensure centos-release-scl-rh is installed on
CentOS when manage_repo is true.

The custom fact to provide the server version doesn't work and also the
bolt task won't work unless the user ensured the SCL is always active.

Add SCL support

These are already in .github/CONTRIBUTING.md