[LIVY-568][BUILD] Upgrade jackson version to 2.9.8
[LIVY-568][BUILD] Upgrade jackson version to 2.9.8

## What changes were proposed in this pull request?

Due to security issues of jackson databind module (https://github.com/FasterXML/jackson-databind/issues/2186) proposing to upgrade jackson version to 2.9.8.

## How was this patch tested?

Existing UTs.

Author: Gyorgy Gal <gal.gyorgy@gmail.com>

Closes #153 from gyogal/LIVY-568.

meisam/incubator-livy,meisam/incubator-livy,meisam/incubator-livy,ajbozarth/incubator-livy,ajbozarth/incubator-livy,ajbozarth/incubator-livy,ajbozarth/incubator-livy,meisam/incubator-livy,meisam/incubator-livy,ajbozarth/incubator-livy,meisam/incubator-livy,ajbozarth/incubator-livy