Check for rel-syndication on a non-post-permalink (e.g. an h-feed)

Described here http://indiewebcamp.com/irc/2015-03-06#t1425670273229

rel-syndication is page-scoped, so including them on an h-feed with multiple h-entrys causes problems.

This of course depends on #13 -- tests for h-feed in general

Read the linked IRC discussion and issue #13 first, then inspect the existing handling of rel-syndication and h-feed markup. Add coverage for an h-feed containing multiple h-entry elements; done means page-scoped rel-syndication is not emitted for a non-post permalink.

Written by the indexing model from the issue text.