Updated content to conform to README best practices template

Before alterations, this content was the module author- determined
description of and instructions for use of the module.

As part of a joint Forge/Docs team effort to standardize formatting and
encourage quality module documentation, a best practices README
template was created via internal and external user testing. That
template was then applied to this module.

I pulled in content from the original README on GitHub and in-code
comments. Standard headings were added (Overview, Module Description,
Setup, Usage, etc.) to organize content, existent content was moved
under its appropriate heading and edited for tone/flow/clarity, and
basic formatting was done to adhere to template standards.
I chose to leave off a Reference section as all bits of the inner
workings of the module are called out and discussed under Usage.
Updated init.pp documentation

This class is largely empty BUT serves a purpose, as @jeffmccune
explained to me. Updated the documentation in the header to reflect
this information.
Fixed typos

Fixed capitalization errors, inserted missing parentheses and missing
dashes, and fixed typos.
Merge pull request #1 from laurenrother/README-update

Updated content to conform to README best practices template