Discontinuation of the Holly branch

Hi firefox-dev, I wanted to let you know that tomorrow's nightly build of Holly will be the last to receive updates. This also means that there will be no further security updates to the channel, and that staying on the channel past Friday, March 14 is not advised. Soon after, the Holly builds will be removed from the FTP servers. Thank you to those who contributed many hours of testing on Holly. Thanks, Jared