Fixes FPM configuration.

Instead of using Ansibles `ini_file` command, which does not allow us to
define the order which configuration options are set on FPM's INI
configuration file, we now use a template with all the default options
in it.

All FPM configuration was moved under `hwr_fpm_config` variable, which
is a list of allowed directives and none of them is required since the
defaults are set on template.

Using the template, makes unecessary the task of compiling the options
for FPM configuration.

Fixes #7 (on GitHub).
More FPM configuration info on README.

Exposes how pool creation works and FPM configuration can be changed,
also shows how to enable or disable FPM installation and configuration
on the role.

Relates to #7 (on GitHub).
Check FPM configuration on CI.

We need to run the check as sudo so it can perform all the needed tasks,
as we previously was having an error on configuration file (syntax)
permissions on log files weren't needed.