Added unlink, hdd, and fixed a typo affecting arrow-left. Python script's desiredGlyphNames array and core_fa.less updated.

Added align-justify, arrows-alt, arrows-left, and exchange. Thank you @OperaManiac for the tip.

Added align-center and align-right to the default icon list in the Python and CSS.

Added instructions to modify the setup_fa.less template file to force the new font files to be downloaded by visitor's browsers.