stop including empty /etc/ilisp/ilisp-keybindings.el so it isn't a conf file

see http://bugs.debian.org/688888 which explains that since the file
is automatically generated by the package configuration scripts, it
cannot be a conf file, since user modifications would not be
preserved.  (Given that the file contains exactly one bit of
information which is the bit set in debconf, I don't think it is worth
trying to preserve manual edits.)
remove debian/ilisp.dirs, no longer needed
fix backquote
missing emacs24 case
restrict write in global .fasl file directory to system group ilisp
canonicalize repo vcs field urls
log changes; close emacs24 bug in changelog