[SPARK-6862] [STREAMING] [WEBUI] Add BatchPage to display details of a batch

This is an initial commit for SPARK-6862. Once SPARK-6796 is merged, I will add the links to StreamingPage so that the user can jump to BatchPage.

Screenshots:
![success](https://cloud.githubusercontent.com/assets/1000778/7102439/bbe75406-e0b3-11e4-84fe-3e6de629a49a.png)
![failure](https://cloud.githubusercontent.com/assets/1000778/7102440/bc124454-e0b3-11e4-921a-c8b39d6b61bc.png)

Author: zsxwing <zsxwing@gmail.com>

Closes #5473 from zsxwing/SPARK-6862 and squashes the following commits:

0727d35 [zsxwing] Change BatchUIData to a case class
b380cfb [zsxwing] Add createJobStart to eliminate duplicate codes
9a3083d [zsxwing] Rename XxxDatas -> XxxData
087ba98 [zsxwing] Refactor BatchInfo to store only necessary fields
cb62e4f [zsxwing] Use Seq[(OutputOpId, SparkJobId)] to store the id relations
72f8e7e [zsxwing] Add unit tests for BatchPage
1282b10 [zsxwing] Handle some corner cases and add tests for StreamingJobProgressListener
77a69ae [zsxwing] Refactor codes as per TD's comments
35ffd80 [zsxwing] Merge branch 'master' into SPARK-6862
15bdf9b [zsxwing] Add batch links and unit tests
4bf66b6 [zsxwing] Merge branch 'master' into SPARK-6862
7168807 [zsxwing] Limit the max width of the error message and fix nits in the UI
0b226f9 [zsxwing] Change 'Last Error' to 'Error'
fc98a43 [zsxwing] Put clearing local properties to finally and remove redundant private[streaming]
0c7b2eb [zsxwing] Add BatchPage to display details of a batch