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 
I'd suggest that using just `['icu_folding']` is likely to give better results here. Compare:

```
$ curl -s 'localhost:9200/_analyze?tokenizer=icu_tokenizer&filters=icu_folding' -d 'ıntəˈnæʃənəl fəˈnɛtık əsoʊsiˈeıʃn'  | json tokens | json -a token
intanaeʃanal
fanetik
asoʊsieiʃn
```

```
$ curl -s 'localhost:9200/_analyze?tokenizer=icu_tokenizer&filters=icu_normalizer,asciifolding' -d 'ıntəˈnæʃənəl fəˈnɛtık əsoʊsiˈeıʃn'  | json tokens | json -a token
intaˈnaeʃanal
faˈnetik
asoʊsiˈeiʃn
```

```
$ curl -s 'localhost:9200/_analyze?tokenizer=icu_tokenizer&filters=icu_folding' -d 'Καλημέρα κόσμε'  | json tokens | json -a token
καλημερα
κοσμε
```

```
$ curl -s 'localhost:9200/_analyze?tokenizer=icu_tokenizer&filters=icu_normalizer,asciifolding' -d 'Καλημέρα κόσμε'  | json tokens | json -a token
καλημέρα
κόσμε
```