implements caseInsensitive option

adding the regex i option if caseInsenstitive is set to true
(this should now reflect the default behavior of datatables
https://datatables.net/reference/option/search.caseInsensitive
```
TabularTables.Books = new Tabular.Table({
. . . . .
  "search": {
    "regex": false, //don't use together with smart
    "search": "", //initial filter on pagerender
    "smart": false, //don't use together with regex
    "caseInsensitive": true // default=true. Set to false for case sensitive search
  }
});
```