Fixed entry URLs to be relative to the current `BlogPage` root.

This fix is needed when:
- django-fluent-pages is used.
- There are 2 ``BlogPage`` models in the page tree.

In such situation, the archive page will correctly display the URLs
relative to the current ``BlogPage`` root.

NOTE: this also upgrades django-tag-parser to the 1.1 release, which has
a backwars incompatible change for `BaseAssignmentOrInclusionNode.get_value()`