SOLR-3913: Optimize the commit/optimize cycle in the PostTool

[epugh]

https://issues.apache.org/jira/browse/SOLR-3913

Description

if you do a opitmize, don't do a commit, otherwise if you request commit do it.

Solution

Be smart about the logic.

Arguably you shouldn't be able to pass in the skip-commit AND the optimize options as the same time...?

Tests

Please describe the tests you've developed or run to confirm this patch implements the feature or solves the problem.

Checklist

Please review the following and check all that apply:

• I have reviewed the guidelines for How to Contribute and my code conforms to the standards described there to the best of my ability.
• I have created a Jira issue and added the issue ID to my pull request title.
• I have given Solr maintainers access to contribute to my PR branch. (optional but recommended, not available for branches on forks living under an organisation)
• I have developed this patch against the main branch.
• I have run ./gradlew check.
• I have added tests for my changes.
• I have added documentation for the Reference Guide