Phrase searching

[María A. Matienzo]

As a user:

• I want to be able to search for a specific phrase which occurs within the text of a resource by wrapping the phrase in double quotes (e.g. "this is my phrase")
• I want my queries for phrases to be insensitive to case and punctuation.
• I want queries that do not contain diacritics to match phrases with those diacritics if they appear (e.g. "forcas armadas indonesias" should match Forças Armadas Indonésias)

[María A. Matienzo]

see also #10

[María A. Matienzo]

We might want to revisit this after working on #56.