helper: improve parsing of command line arguments

Allow a separator argument "--" to separate arguments
provided by openvpn from the arguments provided by the
plugin.

Signed-off-by: Thomas Haller <thaller@redhat.com>
helper: log the command line arguments for "--helper-debug"

Signed-off-by: Thomas Haller <thaller@redhat.com>
helper: pass device type to helper script as command line argument

The device name can be changed, so we should not use it do detect
the device type. Instead pass it to the helper script as argument.

Signed-off-by: Thomas Haller <thaller@redhat.com>
helper: gracefully handle missing environment variables in --up-restart invocations

When calling the script during restart, some environment variables are
not set properly. Work around this by taking the values from the
command line arguments instead.

https://bugzilla.gnome.org/show_bug.cgi?id=556134
https://bugs.launchpad.net/ubuntu/+source/network-manager-openvpn/+bug/280160/
https://bugzilla.redhat.com/show_bug.cgi?id=766340
https://bugzilla.redhat.com/show_bug.cgi?id=1083317

Signed-off-by: Thomas Haller <thaller@redhat.com>
set G_LOG_DOMAIN to nm-openvpn

Signed-off-by: Thomas Haller <thaller@redhat.com>
Merge branch 'th/bgo556134_up_restart'

https://bugzilla.gnome.org/show_bug.cgi?id=556134

Signed-off-by: Thomas Haller <thaller@redhat.com>