initwifi.py script for doing the initial provisioning

[kFYatek]

NOTE: This includes changes from #107. You may want to look there first.

Addresses #74

This adds the initwifi.py standalone script that allows doing the initial provisioning without the need for the official iRobot Home app.

To use it:

1. Turn on your robot
2. Put it in SoftAP mode by holding down both the Home and Spot buttons for a couple of seconds
3. Connect your computer to the SoftAP network (SSID will be something like Roomba-XXXX, with XXXX being the first four characters of the BLID)
4. Run ./initwifi.py, possibly with arguments to your liking
5. If everything goes well, your robot should connect to your network within a minute (acompanied by a friendly sound)
6. You may then proceed with running ./roomba.py to configure it as usual

Tested with my Roomba i3.

Acknowledgement: This heavily draws from @kumy's work from the https://github.com/kumy/Roomba-Wifi-Initial-Provisionning repo. They appear to have a R966 with V2 firmware which, judging from their script, requires plaintext WiFi password. I discovered my i3 with V3 firmware to require it hexlified.