Fix git fetch compatibility with git <1.9; fixes dergachev#9

Git 1.8 and 1.7 will treat `git fetch --all --tags` as `git fetch
--tags`, instead of `git fetch --all`. See github issue.

Author: dergachev

app/models/repository/git_remote.rb

@@ -99,7 +99,7 @@ def ensure_possibly_empty_clone_exists
         return  "Unable to run: git init --bare #{clone_path}"
       end
 
-      unless system "git", "--git-dir", clone_path, "remote", "add", "--tags", "--mirror=fetch", "origin",  clone_url
+      unless system "git", "--git-dir", clone_path, "remote", "add", "--mirror=fetch", "origin",  clone_url
         return  "Unable to run: git --git-dir #{clone_path} remote add #{clone_url}"
       end
     end