6.7.0 Release Candidate 2

This pre-release has following fixes and improvements

Improvements
#232 Improvement: Moved to using a different zip library for opening the zip archives
#898 Improvement: Sigtool uses the version of java bundled with Droid on the Windows OS
#938 Improvement: Internal API result includes whether there is an extension mismatch in identification
#861 Improvement: CSV export has column headers when there is more than one PUID per file
#952 Improvement: SHA512 is available as an option for checksums
#977 Improvement: Added an About Droid dialog to the GUI

Fixes
#953 Bugfix: On CLI, -At and -Wt options without any arguments do not analyse archives or web archives