[SPARK-LLAP-104] Override and shade netty-all dependency (#105)
[SPARK-LLAP-104] Override and shade netty-all dependency (#105)

## What changes were proposed in this pull request?

Currently, spark-llap includes `netty-all` from Apache Hadoop which has different versions from Apache Spark. This PR overrides netty-all depenency to be consist with Apache Spark and also shades that.

## How was this patch tested?

Tested manually in the secure cluster and passed the following non-kerberized Ranger suite additionally.

```
[hive@hdp26-6 python]$ ./spark-ranger-test.py DbTestSuite
....
----------------------------------------------------------------------
Ran 4 tests in 323.545s

OK
[hive@hdp26-6 python]$ ./spark-ranger-test.py TableTestSuite
...................
----------------------------------------------------------------------
Ran 19 tests in 1843.179s

OK
```

This closes #104 
hortonworks-spark/spark-llap,hortonworks-spark/spark-llap,hortonworks-spark/spark-llap