debian/control: changing Vcs URL's to Alioth

The new home for the sogo-connector package is Alioth, so changing the
relevant Vcs-* information.
debian/watch: switch to new upstream version 31
Imported Upstream version 31.0.0
rebuild patch queue from patch-queue branch

added patch:
remove-not-needed-diff-patch-files.patch
document changes and release 31.0.0-1