Updated README to note installation of json-c via package managers for OSX/Linux

    * Installation (if you don't already have OpenSSL installed)

        * Linux (using apt-get)

            * `> sudo apt-get install openssl`

        * Linux (using yum)

            * `> sudo yum install openssl`

        * OSX (using [Homebrew](http://brew.sh/))

            * `> brew install openssl`

* [json-c](https://github.com/json-c/json-c) for JSON-formatted ACL definition files

    * NOTE: Supplied as a Get submodule

    * Installation (via autotools)

        * `> cd vendor/json-c`

        * `> sh autogen.sh`

        * `> ./configure`

        * `> make`

        * `> sudo make install`

    * Installation is further detailed in the json-c README

    * Installation

        * Linux (using apt-get)

            * `> sudo apt-get install json-c`

        * Linux (using yum)

            * `> sudo yum install json-c`

        * OSX (using [Homebrew](http://brew.sh/))

            * `> brew install openssl`

A release of OpenSSL that provides TLS 1.1 or newer is required.

If the OpenSSL installation is not found, the `OPENSSL_PATH` environment

variable may need to be set to its base path, e.g.

`/usr/local/openssl/1.0.1k/`.

`export OPENSSL_PATH=/usr/local/openssl/1.0.1k/`.

Getting Started

---------------