解决向上移动最后一页时出现标题丢失的bug

具体原因应该是vm.js里currendSid监听了pageList,page.js里moveUpPage时会splice pageList，导致pageList的length会临时-1，而这时currentPage还是原length，所以会读出undefined
fixed bug: import data from gist
Merge remote-tracking branch 'origin/develop'