Upgrade Guava dependency and shade Guava in client uber jar

Currently, we depend on Guava 14 which is very old and has security vulnerability (
https://alluxio.atlassian.net/browse/ALLUXIO-3322).

This JIRA aims to achieve two goals:

• upgrade Guava dependency

• shade and relocate Guava dependency in Alluxio client jar to avoid class conflict with other applications