Manual page claims that a missing configuration option for connectivity
interval means "300". That was not the case for a long time (never?).
https://bugzilla.gnome.org/show_bug.cgi?id=723350
Based-on-patch-by: Mathieu Trudel-Lapierre <mathieu.trudel-lapierre@canonical.com>
Add a new 'rc-manager' configuration parameter that allows to select
the strategy used to write resolv.conf; currently supported values
are: none|resolvconf|netconfig, 'none' meaning that NM directly writes
the file.
The default value of the parameter is 'none'; however if a
RESOLVCONF_PATH (or NETCONFIG_PATH) is specified at build time, the
default value will be 'resolvconf' (or 'netconfig').
With this change, NMConfig is really immutable and all
modifyable parts migrated to NMConfigData.
Another advantage is that components can now subscribe to
NMConfig changes to pickup changes to no-auto-default.
The NMConfig class should be immutable and its properties should
not change, with one exception: the NMConfigData property.
Later, when changing/reloading a configuration, NMConfig will only swap
the NMConfigData instance.
The NMConfigData instance itself is also immutable.
