[SPARK-16654][CORE] Add UI coverage for Application Level Blacklisting

Builds on top of work in SPARK-8425 to update Application Level Blacklisting in the scheduler.

## What changes were proposed in this pull request?

Adds a UI to these patches by:
- defining new listener events for blacklisting and unblacklisting, nodes and executors;
- sending said events at the relevant points in BlacklistTracker;
- adding JSON (de)serialization code for these events;
- augmenting the Executors UI page to show which, and how many, executors are blacklisted;
- adding a unit test to make sure events are being fired;
- adding HistoryServerSuite coverage to verify that the SHS reads these events correctly.
- updates the Executor UI to show Blacklisted/Active/Dead as a tri-state in Executors Status

Updates .rat-excludes to pass tests.

username squito

## How was this patch tested?

./dev/run-tests
testOnly org.apache.spark.util.JsonProtocolSuite
testOnly org.apache.spark.scheduler.BlacklistTrackerSuite
testOnly org.apache.spark.deploy.history.HistoryServerSuite
https://github.com/jsoltren/jose-utils/blob/master/blacklist/test-blacklist.sh
![blacklist-20161219](https://cloud.githubusercontent.com/assets/1208477/21335321/9eda320a-c623-11e6-8b8c-9c912a73c276.jpg)

Author: José Hiram Soltren <jose@cloudera.com>

Closes #16346 from jsoltren/SPARK-16654-submit.