Build: Add architecture rule for libshared.a.

- As suggested by Ingo, add libshared.a to the architecture name map.
This allows it to be linked by its short name like other frequently
used libraries.
- Adjust all Jamfiles referencing the lib accordingly.

Add a MIME type to network_settings add-ons

* This is required for localization to work.

Network: moved commonly used classes into app.

* This way all add-ons share the same code, and also the same
translations.

Network: SSH list item now indicates a running server.

* This will be moved into the network preferences, so that it can be
used from other add-ons, as well.

Network/SSHService: Moved base ServiceView into its own file.

* SSHServiceView now subclasses it for SSH specific functionality.

Network: SSH service add-on now creates sshd user.

* If it does not exist yet, the sshd user is created upon enabling
the service.
* Also, it now uses kMsgIsServiceRunning to determine the current
label/function of the enable/disable button.

Network: first steps to an SSH service add-on.

Network: moved commonly used classes into app.

* This way all add-ons share the same code, and also the same
translations.

Network: SSH list item now indicates a running server.

* This will be moved into the network preferences, so that it can be
used from other add-ons, as well.

Network/SSHService: Moved base ServiceView into its own file.

* SSHServiceView now subclasses it for SSH specific functionality.

Network: SSH service add-on now creates sshd user.

* If it does not exist yet, the sshd user is created upon enabling
the service.
* Also, it now uses kMsgIsServiceRunning to determine the current
label/function of the enable/disable button.

Network: first steps to an SSH service add-on.