New source: pleaserun

[jordansissel]

The pleaserun tool helps generate service manifests for different service platforms such as systemd and runit.

This PR introduces pleaserun as a package source. The goal is to have a package you can install that will "do the right thing" and install the best-fitting service manifest for the target system.

Example usage:

% fpm -s pleaserun -t rpm -a all -n redis-service --pleaserun-name redis /usr/bin/redis-server
...

% sudo yum install redis-service-1.0-1.noarch.rpm
...
  Installing  : redis-service-1.0-1.noarch                                                            1/1
Platform systemd (default) detected. Installing service.
To start this service, use: systemctl start redis
  Verifying   : redis-service-1.0-1.noarch                                                            1/1

Installed:
  redis-service.noarch 1.0-1
...

% systemctl status redis
● redis.service - redis
   Loaded: loaded (/usr/lib/systemd/system/redis.service; disabled; vendor preset: disabled)
   Active: inactive (dead)

Yay, easy services!

It also tries to clean up during package removal:

% sudo yum remove redis-service
...
Running cleanup to remove service for package redis-service
...

% sudo systemctl status redis
● redis.service
   Loaded: not-found (Reason: No such file or directory)
   Active: inactive (dead)

[untergeek]

👍

[jordansissel]

Specs reasonably passing for me. This PR adds no meaningful tests, but that's partly because I'm still trying to figure out a nice way to actually test it.