shell: Freeze network settings while editing them

So that external changes don't interfere with the user interaction.

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Remove erronous argument to configure_bond_settings

This argument is unset and unused, likely a copy/paste error.

Reviewed-by: Stef Walter <stefw@redhat.com>
shell, NM model: Consistently use 'settings.foo_bar' instead of 'settings["foo-bar"]'

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Refactor network settings summaries

Simplify the code, and show them as multiple rows instead of one long
parapgraph.

Reviewed-by: Stef Walter <stefw@redhat.com>
shell: Support for network bridges

Fixes #459
Closes #988
Reviewed-by: Stef Walter <stefw@redhat.com>