Pass '--vcs' parameter to echangelog to avoid different decisions.

As reported on github #4, it is possible that with mixed-VCS repos
sunrise-commit will prefer a different VCS than echangelog would do. To
avoid that, always pass our VCS to echangelog.

sunrise-commit.in

@@ -437,7 +437,8 @@ main() {
 
 				if [ -z "${trivial}" ]; then
 					sayv '...and appending to it.'
-					echangelog "${commitmsg}" || die 'Please correct the problems shown by echangelog.'
+					echangelog --vcs ${SC_VCS} "${commitmsg}" \
+						|| die 'Please correct the problems shown by echangelog.'
 					echo
 				fi