bins: fix permissions issue regenerating albums

since the template files in the nix store are read-only, they can't be
overwritten the second time the album is generated.  using cp's '-f'
option works around this.

pkgs/tools/graphics/bins/cp-dash-f.patch

@@ -0,0 +1,11 @@
+--- a/bins	2016-05-18 20:45:49.513330005 -0400
++++ b/bins	2016-05-18 20:58:58.957830874 -0400
+@@ -1332,7 +1332,7 @@
+                 mkdir $destDir, 0755
+                     or die("\nCannot create $destDir: $?");
+             }
+-            system("cp", "-R", bsd_glob("$staticDir/*", GLOB_TILDE), "$destDir") == 0
++            system("cp", "-Rf", bsd_glob("$staticDir/*", GLOB_TILDE), "$destDir") == 0
+                 or die("\nCannot copy $staticDir directory content to $destDir: $?");
+         } else {
+             beVerboseN("  Cannot find any static template directory.", 4);

pkgs/tools/graphics/bins/default.nix

@@ -23,7 +23,8 @@ stdenv.mkDerivation {
                                      DateTimeFormatDateParse ]; #TODO need Gtk (not Gtk2?) for bins-edit-gui
 
   patches = [ ./bins_edit-isa.patch
-              ./hashref.patch ];
+              ./hashref.patch
+              ./cp-dash-f.patch ];
 
   installPhase = ''
     export DESTDIR=$out;