Use plain ASCII for License.

The current file uses © (correct UTF copyright symbol), but when
generated into the build artifacts (as ASCII text) it looks garbled (`//
Copyright: Â©2011-2013`).

Resolves #1491.

References: 
* http://www.copyright.gov/circs/circ01.pdf
* http://stackoverflow.com/questions/221376/putting-copyright-symbol-into-a-python-file#221380