fix maintainer information s/maintainer/maintainers

pkgs/applications/editors/bluefish/default.nix

···
     description = "A powerful editor targeted towards programmers and webdevelopers";
     homepage = http://bluefish.openoffice.nl/;
     license = licenses.gpl3Plus;
-    maintainer = [maintainers.vbgl];
+    maintainers = [maintainers.vbgl];
     platforms = platforms.all;
   };
 }

pkgs/applications/graphics/yed/default.nix

···
     homepage = http://www.yworks.com/en/products/yfiles/yed/;
     description = "A powerful desktop application that can be used to quickly and effectively generate high-quality diagrams";
     platforms = jre.meta.platforms;
-    maintainer = with maintainers; [ abbradar ];
+    maintainers = with maintainers; [ abbradar ];
   };
 }

pkgs/os-specific/linux/macchanger/default.nix

···
 
   meta = {
     description = "A utility for viewing/manipulating the MAC address of network interfaces";
-    maintainer = with stdenv.lib.maintainers; [ joachifm ];
+    maintainers = with stdenv.lib.maintainers; [ joachifm ];
     license = with stdenv.lib.licenses; gpl2Plus;
     homepage = "https://www.gnu.org/software/macchanger";
     platform = with stdenv.lib.platforms; linux;

pkgs/tools/X11/primus/default.nix

···
   meta = {
     homepage = https://github.com/amonakov/primus;
     description = "Faster OpenGL offloading for Bumblebee";
-    maintainer = maintainers.coconnor;
+    maintainers = maintainers.coconnor;
   };
 }

pkgs/tools/networking/openvpn/update-resolv-conf.nix

···
   meta = with stdenv.lib; {
     description = "Script to update your /etc/resolv.conf with DNS settings that come from the received push dhcp-options";
     homepage = https://github.com/masterkorp/openvpn-update-resolv-conf/;
-    maintainer = maintainers.abbradar;
+    maintainers = maintainers.abbradar;
     license = licenses.gpl2;
     platforms = platforms.unix;
   };