Use "document noun title" if no placeholder

After the work in b223db47d4e4b291f88959fb9ef88a302a58f3ed, Finders
without a placeholder specified used nil. This commit correctly uses the
fetch to return document_noun title if no placeholder is provided.
Merge pull request #104 from alphagov/correctly-show-document-noun-if-no-placeholder

Use "document noun title" if no placeholder