Readme suggestion - pretty print all getInfo keys

[surfaceowl]

The getInfo method returns a nice dict with all the device info of a raspberry pi. The current example in the Readme shows the user how to retrieve a single key/value pair - but the user may not know all values available from pirev.

It may be helpful to add an example in the Readme, which pretty prints all results returned by getInfo. The example below uses the json library to do this (already part of the standard Python library), and keeps with the zero-dependency goal of this project:

In [2]: from pirev.pirev import getInfo

In [3]: info = getInfo()

In [4]: import json

In [5]: print(json.dumps(info, indent=2))
{
  "cpus": [
    {
      "processor": 0,
      "model_name": "ARMv6-compatible processor rev 7 (v6l)",
      "bogomips": 797.66,
      "features": "half thumb fastmult vfp edsp java tls",
      "cpu_implementer": 65,
      "cpu_architecture": 7,
      "cpu_variant": 0,
      "cpu_part": 2934,
      "cpu_revision": 7
    }
  ],
  "hardware": "BCM2835",
  "revision": {
    "type": "B",
    "memory": "256 MB",
    "processor": "BCM2835",
    "revision": 1.0,
    "manufacturer": "Egoman",
    "code": 3
  },
  "serial": "00000000e96a5c9e",
  "model": "Raspberry Pi Model B Rev 1"
}