On traits and yields pages combine n, stat and statname columns

See <a href = "https://ebi-forecast.igb.illinois.edu/redmine/issues/2300">Redmine #2300</a>
The whitespace consisting of the newline character at the end of the previous line and the leading whitespace on this line will all appear in the result that the server returns to the browser.  This will be rendered as a single space before the comma by the HTML renderer.  But we don't really want to see a space before the comma, we only want one following the comma.

This whole section consisting of the nested `if` statements and the following `if` statement is a good candidate for being factored out into some controller code, or probably better, into a helper.  That way you could replace eight `<% %>` blocks with just one.  Have the helper method create exactly the string of mixed HTML markup and text that you want, and then call it here to display it.

You could just return a text string (e.g. "SD = 2.7482, n = 1") from the method, but I recommend adding some HTML markup as well to solve what I see as another problem: I think line-breaking should only occur after the comma and not before or after an `=` sign.  To do this, you would return something like `"<span class='...'>SD = 2.7482,  </span><span class='...'>n = 1</span>"` and give class "..." some CSS style that prevents line breaking.  Alternatively, you could just use non-breaking spaces (`&nbsp`) for all spaces except for the one after the comma.