caltechlibrary/microarchiver: Release 1.7.0 – New features and changes

* Store JATS XML for each article, as well as any image referenced in the JATS data. Images are converted to uncompressed TIFF before being stored. * Perform JATS validation for each article by default. * Add `-X` option to disable automatic JATS DTD validation. * Change `-a` option to accept a file containing either a list of DOIs or the XML format sent by micropublication.org. * Change exit code numbering scheme. * Communicate number of failures in terms of exit codes; see [README](README.md) for more details. * Test if date given to `-d` is syntactically correct but not a valid date. * Refactor and change some internal code. * Fix miscellaneous bugs. The file [CHANGES](CHANGES.md) contains a more complete change log that includes information about previous releases.