Enable secure mode by default

[drbild]

The last thing missing from a fully functioning firmware is enabling the wifi and xbridges service by default.

For the latter, we need to cherry-pick one commit from this PR - xaprw: enable secure-mode xbridge on boot

For the WiFi, we need to decide how to manage the credentials. I see two options.

1. Merge the Xaptum-Guest wifi credentials into master, since most of our work happens in the office. I don't mind if that password appears in the private git repo history.

   For now, when provisioning a firmware for a customer, we'll need to change the default credentials to theirs and rebuild the firmware.

   Once Fej has the captive daemon ready, we can connect to the Xaptum wifi and then change the credentials via the control channel.

2. Keep the credentials commit off of master on separate branch. When building a firmware, that commit needs to be cherry-picked (or rebased) onto the active branch.

[drbild]

Closed by #81