WIP Normalize for diacritics

PR branch for #729

Tasks to do
- [x] unicode normalization client side for page search with unorm and xregexp
- [x] unicode normalization for ES queries, setting up analyzers
- [x] unicode normalization for backend stream
- [x] add tests
- [ ] launch a showcase dokku instance 
:+1: As I said in the comments above:

> What we ultimately want, I think, is to do ICU folding but not ASCI folding. ASCII folding will lose all unicode characters, but we want to keep the ones that don't have normalizations. For instance, Kanji characters remain as unicode after ICU folding whereas I don't believe they have have ASCII equivalents (transliteration is a different thing).