[#1983294]: Better support for unassigned issues:
- Use uid 0 for unassigned, not a NULL value (better for D6 migration).
- Make the assigned field required and default to uid 0.
- Alter the widget so that the label for uid 0 is t('Unassigned').
- Use token_formatters for displaying field_issue_assigned when
creating the default issue node type.
- Fixed a few minor bugs in the custom token from commit d965f22cd7.
[#1979000]: Ported issue tag support to D7
- Injected a setting on vocabulary forms to select if the vocab should
be used for the issue queues (and if so, what widget to use for the
- Ported _project_issue_views_add_taxonomy_filters() to D7 and we use
it to build the advanced search default views instead of the bogus
taxonomy_vocabulary_9_tid filter that was hard-coded.
- Alter in a new term URI callback to the term entity that checks if
the term is from an issue queue-enabled vocab. If so, link to the
site-wide advanced search, else fallback to taxonomy_term_uri().