Refix #293 for <Leader> and <LocalLeader> mappings

Shougo, 
Sorry for the previous pull request. I rework the refix. I have tested the fix with `<Leader>`, `<LocalLeader>`, `<CR>`, `<Enter>`,  `<F1>` ~ `<F12>`, `<Up>`, `<Down>`, `<Left>`, `<Right>` and the combinations of them all. Please help to check the pull request. Thanks!

liangfeng