[SPARK-LLAP-45] Bump to 1.0.4-2.1 and support `publish` (#47)
[SPARK-LLAP-45] Bump to 1.0.4-2.1 and support `publish` (#47)

## What changes were proposed in this pull request?

This PR bumps the version to 1.0.4-2.1 and support `publish`.

## How was this patch tested?

```
$ ./build/sbt publish -Drepourl=... -Duser=... -Dpassword=...
...
```

This closes #45 .
hortonworks-spark/spark-llap,hortonworks-spark/spark-llap,hortonworks-spark/spark-llap