Enhance job ui in spark ui system with adding pool information

Enhance job ui in spark, now it will support following three scenarios
1. For FIFO scheduling, job page will similar with original one with adding some summary info and empty pool table for FIFO scheduling
![fifo](https://f.cloud.github.com/assets/1168928/786604/d9bda662-eabd-11e2-8ccd-e3f8f2b07ad5.png)
2. For Fair scheduling, job page will show all pools info with minishare, weight, active stage number and all active/completed/failed stage info with pool name link
![fair](https://f.cloud.github.com/assets/1168928/786623/e030f17e-eabe-11e2-9e4d-e8f13ba3bb6e.png)
3. In Fair shceduling mode, pool name in pool table and stage table will link to pool detail page, pool detail page will show detail info with its active stages for specific pool.
![pooldetail](https://f.cloud.github.com/assets/1168928/786627/28592f52-eabf-11e2-85c2-056e0ed24318.png)