Create post installation for deb package

[vpetersson]

The Debian package should do the following things:

• Run wott-agent to initiate the package
• Print out a post-installation message

Post installation message

Thank you for installing the wott-agent. Your device's unique ID is: [device id]

To unleash the value of WoTT, and to gain insight into the security of your device(s), sign up for an account at http://dash.wott.io.

You can claim your device in the dashboard by visiting:
[device claim URL]

For more information on how to get started, visit wott.io/getting-started

[AlEsmail]

Good job installing the wott-agent and welcome to the community of security conscious hardware devs!

You're one step closer to building a secure device. Your device's unique ID is: [device id]

To unleash the value of WoTT, and to gain insight into the security of your device(s), connect your device at https://dash.wott.io.

You can claim your device in the dashboard by visiting:
[device claim URL]

For more information on how to get started, visit wott.io/getting-started or drop me a line at hey@wott.io.

Best!
Viktor

[vpetersson]

Works, but I wouldn't sign it off with my name as it is a message from the team.

[a-martynovich]

@vpetersson How about we let this message be produced by agent, not by postinstall script? The script will just invoke agent (with some --arg if needed). This way it will be a lot simpler.

Otherwise I'll have to extract deviceId and claimURL to put them in the message. That's ugly and will break in the future.

[vpetersson]

@a-martynovich Yeah that's fine by me.

[a-martynovich]

This issue depends on #44 now.