Fix #663 - Bugzilla to GitHub Issues migration

All references to "our Bugzilla" or bugs.dwscoalition.org have been modified to reflect the move to GitHub Issues.

Due to the wiki page linking to the CLA as a bugzilla attachment, I've been unable to sign one.  I've sent an email requesting a copy, but in the meantime I am entirely happy to assign copyright to these changes to Dreamwidth Studios, if that'll get the bug fixed quicker.  It's not like I have any need to retain copyright on such piddling little alterations.