Added FontAwesome support. Cosmetic changes.

* Added support for the "useFontAwesome" boolean setting.

* Added a missing semicolon in lib/reactive_table.js .

* Changed filter input appearance, from an inline-form to an
  input-group. The left part's content of the input group is the
  localized filer string by default, a fa-filter if useFontAwesome
  is set to true.
  Since by default an input group has width = 100%, I gave it
  col-sm-4 col-sm-offset-8 classes. Floating it right in
  lib/reactive_table.css is therefore no longer needed.

* Changed sorting icons. If useFontAwesome is set to true,
  fa-sort-{desc,asc} will be used.
Updated leaderbard example to use FontAwesome.
Fixed bug, normalized quote usage.

If a click event fires on the <i> element on the table's top row
(i.e. the FontAwesome icon), then the event handler gets the wrong
event.target, which causes an error.

I also changed all double quotes into single quotes (except for the
two double quotes inside the filter regExps). I personally prefer
double quotes, but there were 76 ' and 56 ", so...
I just wanted to normalise because it was driving me mad. :-P
Removed placeholder in filter input field if FontAwesome is not used.
Merge pull request #48 from pscanf/master

FontAwesome support