Make checksum comparison case insensitive, fixes #142

[luis100]

Please ensure you have completed the following before submitting:

• [ ] Ran all tests to ensure existing functionality wasn't broken
• [ ] Ran all quality assurance checks and fixed any new errors or warnings, which include:

• PMD
• FindBugs
• Jacoco code coverage

Note: you can complete both boxes by running and fixing warnings/errors with gradle clean check

• [x] Code is self documenting or a short comment when self documenting isn't possible