Add hplip and enable remote printing

[rahul-thakoor]

• Enable printer sharing and allow printing from internet in Server settings by default
• Add a startup message
• Add hplip package which provides support for numerous popular hp printers

closes #1

[rahul-thakoor]

According to the documentation :

The Listen directive is similar to the Port directive but allows you to restrict access to specific interfaces or networks

Let me change it back actually. I think using different directives together can cause issues.

[rahul-thakoor]

I can confirm it works with iOS, macOS, Android and Windows

[rahul-thakoor]

@willswire would you happen to know if the order of the Listen directives matter?

using

Listen 80
Listen 631

on Android in detects the printer but cannot get it's information or send print job while swapping to

Listen 631
Listen 80

works immediately. I'm not sure if this is related to my device or the case for all

[willswire]

@rahul-thakoor not sure, although I would say let's just go with the second ordering as it works. Also, I am getting a merge conflict for the Dockerfile - could you reformat and commit that file so I can merge this PR online?

[rahul-thakoor]

I'm keeping the original ordering since it breaks other platforms.

Let's see if others experience this issue with Android devices then we can tackle it. Thanks a lot Will

[willswire]

Thank you for the changes!