Implement .truncate() function as jQuery plugin

[#44616153]

It truncates text inside given element, so its width doesn't exceed
specified value (in pixels). Note that you *can* use this function
even on elements like <p> or <h1>, which quite often have width of its
parent (not width of their text). This function will create a new
<span> element with the same style as original text and use it to
measure real width of the text.
Truncate bar graph title when it's too long using new truncate plugin

[#44616153]