[SPARK-4329][WebUI] HistoryPage pagenation

Current HistoryPage have links only to previous page or next page.
I suggest to add index to access history pages easily.

I implemented like following pics.

If there are many pages, current page +/- N pages, head page and last page are indexed.

![2014-11-10 16 13 25](https://cloud.githubusercontent.com/assets/4736016/4986246/9c7bbac4-6937-11e4-8695-8634d039d5b6.png)
![2014-11-10 16 03 21](https://cloud.githubusercontent.com/assets/4736016/4986210/3951bb74-6937-11e4-8b4e-9f90d266d736.png)
![2014-11-10 16 03 39](https://cloud.githubusercontent.com/assets/4736016/4986211/3b196ad8-6937-11e4-9f81-74bc0a6dad5b.png)
![2014-11-10 16 03 49](https://cloud.githubusercontent.com/assets/4736016/4986213/40686138-6937-11e4-86c0-41100f0404f6.png)
![2014-11-10 16 04 04](https://cloud.githubusercontent.com/assets/4736016/4986215/4326c9b4-6937-11e4-87ac-0f30c86ec6e3.png)


Minor, but I actually think this doesn't need to be in its own method. It's probably clearer if the HTML is in here directly. Right now it's not clear why it's floating right from first glance.