[ZEPPELIN-890] Cache downloaded file from 'maven-download-plugin'

[Leemoonsoo]

What is this PR for?

Cache downloaded file from 'maven-download-plugin' to improve CI build speed and reduce build failure due to network issue.

What type of PR is it?

Improvement

Todos

• - Cache '.m2/repository/.cache/maven-download-plugin' directory

What is the Jira issue?

https://issues.apache.org/jira/browse/ZEPPELIN-890

Questions:

• Does the licenses files need update? no
• Is there breaking changes for older versions? no
• Does this needs documentation? no

[prabhjyotsingh]

One more suggestion not sure if that is relevant to this PR should we have <retries>5</retries> near https://github.com/apache/zeppelin/blob/master/spark-dependencies/pom.xml#L827 and
https://github.com/apache/zeppelin/blob/master/spark-dependencies/pom.xml#L907 ?

[Leemoonsoo]

@prabhjyotsingh Thanks for suggestion. Once travis caches '.m2/repository/.cache/maven-download-plugin' directory, 'maven-download-plugin' will not even try to download files from internet. So i think i'll be okay without increasing retry count.

[prabhjyotsingh]

Thank you for the explanation, I understand it now.
LGTM.

[Leemoonsoo]

Merge if there're no further discussions

[prabhjyotsingh]

Sure, I think we can merge this as a hotfix.

[khalidhuseynov]

LGTM