Add date/time stamp to charts

[evanwolf]

Problem: We've already seen our maps and charts screencapped. http://www.oakmayor2014.com/voter-information/campaign-finances/#toggle-id-1 While we update them, their screencaps are snapshot history. This lets different sites tell different stories using our data.

Action: So let's add a small date/time stamp (or last updated date/time) along with a "cc-by YYYY OpenOakland" to the original.

[tdooner]

We have different definitions of "bug". Let's reserve that tag for things that are negatively impacting the existing experience of our existing features.

As for the usefulness of this enhancement, I'm not sure this is the most effective way to combat this. Readers of online newspapers should know that the article was published on a given date, and not modified thereafter. But, whatever.

[evanwolf]

fair enough. it's a design defect when our work can be misleading or, in this case, easily used in a misleading way.