[meta] Add task for syncing submodules

Rakefile

@@ -1,5 +1,3 @@
-# rsync -avz --exclude 'Newest Additions' --exclude '*.DS_Store' . ~/Dropbox/wallpapers/dlanham\ wallpapers
-
 namespace :clean do
   desc 'Remove .DS_Store files from Dropbox'
   task :ds_store do
@@ -13,8 +11,19 @@ namespace :sync do
   desc 'Sync David Lanham wallpapers (assumes the unzipped updates are in ~/Downloads)'
   task :dlanham do
     FileList[File.expand_path('~/Downloads/dlanham*')].each do |dir|
-      Dir.chdir dir
+      Dir.chdir dir do
         sh 'rsync -avz --exclude "Newest Additions" --exclude "*.DS_Store" . ~/Dropbox/wallpapers/dlanham\ wallpapers'
       end
+      rm_r dir
+    end
+  end
+
+  desc 'Sync submodules'
+  task :submodules do
+    sh 'git submodule foreach git pull'
+    Dir.chdir 'src/prezto' do
+      sh 'git fetch upstream'
+      sh 'git rebase upstream/master'
+    end
   end
 end