Remove AND on a positive filter in explore view and use simple quotes

[fmassot]

In the explore view, it is possible to filter on a field value by clicking on the magnifying glass.

When filtering, we add the string AND field:"value" to the query.

Instead, with should add the string field:'value' to the query and AND is the default operator and single quote works even on fields where positions are not stored.

[ddelemeny]

Single quoted terms aren't friendly to the lucene parser either... Do we target fixing the whole bunch of parser issues for 0.5 ?

[fmassot]

I see, we can at least remove the AND. The PR which fixes some issues on the QL will be soon merged, hopefully tomorrow.