The image downloading is tied to tftp and handled by the proxy. Since
puppet-foreman_proxy is already able to download images there's no sense
in duplicating the code here.

Based on #486

Closes GH-580
Closes GH-581

* Try tree times before giving up when sending report to Foreman.
* Add retry tests to the report processor

closes GH-534
closes GH-535

Fixes GH-593

Recently, version 2.0.0 was released and it does not contain any
breaking changes. See https://forge.puppet.com/puppet/extlib/changelog#v200-2017-10-11
for details.

Currently puppet module list --tree throws following warnings because of
this:

Warning: Module 'puppet-extlib' (v2.0.0) fails to meet some dependencies:
  'theforeman-foreman' (v8.1.0) requires 'puppet-extlib' (>= 0.10.4 < 2.0.0)

Enables setting of unattended_url during install with foreman-installer

Installation of the plugins can influence the API
and the apipie cache needs to be refreshed after that.

Change working directory to the determined home directory of
`puppetuser` before continuing to ensure we don't reside in /root or
anywhere else we don't have permissions.

Fixes issue #611.

The dynflow service was moved into core with 1.17. That renamed it to
dynflowd and means the service should be started by default.

For compatibility parameters are provided. This means we must move the
service name detection to the jobs.pp file because that's the only place
we know the actual value.