Make the formula fully pillar driven/customizable

- split package and param into separate state files
- use defaults.yml to specify all configurable options of the formula
- setup map.jinja to read in defaults.yml, filter by os_family for
  Arch, and merge in sysctl:lookup pillar
- Updated README

sysctl/package.sls

@@ -0,0 +1,10 @@
+# -*- coding: utf-8 -*-
+# vim: ft=sls
+
+{## import settings from map.jinja ##}
+{% from "sysctl/map.jinja" import sysctl_settings with context %}
+
+sysctl-pkg:
+  pkg.installed:
+    - name: {{ sysctl_settings.pkg }}
+    - failhard: True