Fix CSV for Excel

Problem/Motivation

The export of signatures to CSV puts a space before each quoted field, like this:
"name", "firstname", "title", "zip", "town", "country"
"Smith", "Joe", "", "10018", "New York", "USA"
"Jones", "Mike", "", "98204", "Los Angeles", "USA"

When loading in Excel 2010, the extra spaces cause all the quotes to be treated as literals, instead of just protecting the fields from stray commas.
This requires a lot of effort to fix if the file will be processed further in Excel, like preparing for printing.

Proposed resolution

I have attached a patch to 6.x-2.x that removes the extra spaces.