1.
There was an inconsistency with creating a file
/etc/systemd/system/redis-server.service.d/limit.conf
but then referring to file
/etc/systemd/system/redis-server.service.d/limits.conf
in the augeas resource.

Whereas limits.conf seems to be a better name the file
limit.conf is now likely to exist on many systems, and
I don't want to risk having both a limit.conf and a
limits.conf. So limit.conf it is.

2.
The context was set to to the filepath, but should have been
prefixed with "/files". Seeing as this is default I removed the context.

3.
In discouse with the documentation it is *not* possible to
set the value of the path with "defnode", so the solution here
with following up with "set" is left as this works correctly.

This closes  #268

The puppetlabs/apt version 5 adds fixes for Ubuntu 18.04.

The newest winrm-fs version is not compatible with ruby<2.20. This
commit ensures that the newest winrm-fs version is installed that
is still compatible with ruby ">=1.9 <2.2".

Lint and rubocop (autofixes only)

Also add puppet 6 vendored `core` types.

Fix needed for change made in #279