Use comma rather than space delimiters in preserve_tags
Use upgrade mechanism to upgrade saved tag list.
Fix code formatting
Merge branch 'sophist_change_preserve_tags_delimiter_to_comma' of git://github.com/Sophist-UK/picard into Sophist-UK-sophist_change_preserve_tags_delimiter_to_comma

Bump Picard version to 1.3.0dev2 and update config upgrade hooks