highlight filter broken for numeric items

[dontgitit]

#1281 fixed for numeric matchItem; however it's still broken with a numeric query. Can use the same fix as for matchItem;

https://github.com/angular-ui/ui-select/blob/master/src/common.js#L132

    return queryToEscape.replace(/([.?*+^$[\]\\(){}|-])/g, '\\$1');

to

    return ('' + queryToEscape).replace(/([.?*+^$[\]\\(){}|-])/g, '\\$1');