Use geojsonio.py to send the data to geojson.io

This will send the geojson output to http://geojson.io via a GitHub gist,
it will then open up a browser on the geojson.io page.
Add boolean condition for geojsonio

Send data to http://geojson.io if 'geojsonio' is set to 'True'
Fix comparison to True
Switch from argv to argparse and define switches

Replace 'sys.argv' with 'argparse.ArgumentParser', replace 'config_file'
argument and add an argument for sending data to geojson.io
Add description to --help and fix a spelling error
Update readme with info on command line switches
Replace args.* tests with parser.add_argument

This replaces the tests for defining an aternate config file and
sending the geojson to geojson.io, by using the parser.add_argument
'dest and 'default' options.
Handle geojsonio.py import exceptions

This will print a message telling where to get the modules you need
if you try to run 'archmap.py' without 'github3.py' or 'geojsonio.py'.
Print out basic information when archmap.py is run

This will print out details of what 'archmap.py' is about to do.