python: use gi.require_version() in generate-setting-docs.py and examples

gi now emits a warning when not loading a specific library
version [1]:

  ./generate-setting-docs.py:21: PyGIWarning: NM was imported without specifying a version first. Use gi.require_version(NM, 1.0) before import to ensure that the right version gets loaded.
    from gi.repository import NM, GObject

Seems require_version() is reasonably old to just always use it without
breaking on older versions [2].

[1] Related: https://bugzilla.gnome.org/show_bug.cgi?id=727379
[2] https://git.gnome.org/browse/pygobject/commit/?id=76758efb6579752237a0dc4d56cf9518de6c6e55

examples/python/gi/add_connection.py

@@ -29,6 +29,8 @@
 # https://developer.gnome.org/NetworkManager/1.0/ref-settings.html
 #
 
+import gi
+gi.require_version('NM', '1.0')
 from gi.repository import GLib, NM
 import sys, uuid
 

examples/python/gi/deactivate-all.py

@@ -31,6 +31,8 @@
 #
 
 import sys
+import gi
+gi.require_version('NM', '1.0')
 from gi.repository import NM
 
 # suported connection types

examples/python/gi/device-state-ip4config.py

@@ -21,6 +21,8 @@
 #
 
 import sys
+import gi
+gi.require_version('NM', '1.0')
 from gi.repository import GLib, NM
 
 #

examples/python/gi/firewall-zone.py

@@ -20,6 +20,8 @@
 #
 
 import sys
+import gi
+gi.require_version('NM', '1.0')
 from gi.repository import GLib, NM
 
 #

examples/python/gi/get-active-connections.py

@@ -21,6 +21,8 @@
 
 # This example lists currently active connections
 
+import gi
+gi.require_version('NM', '1.0')
 from gi.repository import GLib, NM
 
 if __name__ == "__main__":

examples/python/gi/get-lldp-neighbors.py

@@ -21,6 +21,8 @@
 #
 
 import sys
+import gi
+gi.require_version('NM', '1.0')
 from gi.repository import GLib, NM
 
 #  This example shows how to get a list of LLDP neighbors for a given interface.

examples/python/gi/get_ips.py

@@ -21,6 +21,8 @@
 #
 
 import sys, socket
+import gi
+gi.require_version('NM', '1.0')
 from gi.repository import GLib, NM
 
 #

examples/python/gi/list-connections.py

@@ -20,6 +20,8 @@
 # Copyright 2012 - 2014 Red Hat, Inc.
 #
 
+import gi
+gi.require_version('NM', '1.0')
 from gi.repository import NM
 
 # This example asks settings service for all configured connections.

examples/python/gi/show-wifi-networks.py

@@ -21,6 +21,8 @@
 #
 
 import locale
+import gi
+gi.require_version('NM', '1.0')
 from gi.repository import NM
 
 #

examples/python/gi/update-ip4-method.py

@@ -27,6 +27,8 @@
 # https://developer.gnome.org/NetworkManager/1.0/ref-settings.html
 #
 
+import gi
+gi.require_version('NM', '1.0')
 from gi.repository import GLib, NM
 import sys, socket