Readme colons

I think the README looks funny with two colons after 'Author', 'Copyright', and 'License' (at least when rendered in Github-flavored markdown).  I propose changing it to one, as per this pull request.

I also found that there was a test that was failing when the suite was run outside of 2013, so I stubbed Time.now to make it work in any year.  This is in a separate commit because it's logically separate; let me know if you'd prefer for me to issue two separate pull requests instead of one.