Make key:value searches case insensitive

[michaelwood]

For example:

beneficiaryLocation.countryCode:gb
vs
beneficiaryLocation.countryCode:GB

This is only true where the field is a keyword type.

https://github.com/ThreeSixtyGiving/grantnav/blob/live/dataload/import_to_elasticsearch.py#L68

Any fields that is {"type": "keyword"}, are exact matches and any which are {"type": "text"}, will be interpreted in a fuzzier way (case insensitive, can cope with whitespace, punctuation etc)

Possible lines of enquiry:

• custom analyser type to the index
• application side OR the permutations of cases