search: introduce loading custom fusejs options from site config #134

* refer https://fusejs.io/api/options.html for opts
* keys used can be some, all or none from
   ["title", "permalink", "summary", "content"]

in config.yml, add fuseOpts as shown below =>
  params:
    fuseOpts:
        isCaseSensitive: false
        shouldSort: true
        location: 0
        distance: 1000
        threshold: 0.4
        minMatchCharLength: 0
        keys: ["title", "permalink", "summary", "content"]

assets/js/fastsearch.js

@@ -23,6 +23,7 @@ function loadSearch() {
                             'content'
                         ]
                     };
+                    {{ if . }}options = {{ jsonify . }}{{ end }} // load custom options from .Site.Params.fuseOpts
                     fuse = new Fuse(data, options); // build the index from the json file
                 }
             } else {