Add ability to see at a glance if a contribution is part of a recurring series

We have a request to see 'at a glance' if a contribution is recurring. This seems like a generally useful thing. My thinking is that if we use an icon we can add this with the minimum real-estate. The icon in the image has hover text of 'Recurring payment'. If clicked it pops up a 'View Contribution Recur' for the correct contribution.

Using the sort arrows results in things being ordered by contribution_recur_id. I think this has the same effect as what people might expect (sort by whether there is a contribution_recur_id) and is mildly more useful

The image is from here - http://fontawesome.io/cheatsheet/ - open to a different one