Adding TinyNav.js

Description: TinyNav.js is a tiny jQuery plugin (452 bytes minified and
gzipped) that converts <ul> and <ol> navigations to a select boxes for
small screen.
Source: https://github.com/viljamis/TinyNav.js
Author: Viljami Salminen
License: MIT
Merge pull request #3341 from JGallardo/master

Adding TinyNav.js