Add --bump release logic

Closes https://git.autonomic.zone/coop-cloud/abra/issues/173.

abra

@@ -2097,7 +2097,6 @@ sub_recipe_release() {
 
   if [ "${#RECIPE_VERSIONS[@]}" -gt 0 ]; then
     latest_version="${RECIPE_VERSIONS[-1]}"
-    debug "Detected '${RECIPE_VERSIONS[@]}' as the latest version"
     if [ "$force" = "true" ]; then
       latest_version_message=$(git tag -l "$latest_version" --format='%(contents)')
     else
@@ -2110,7 +2109,7 @@ sub_recipe_release() {
     latest_version_message="Initial tagged release"
     info "No previous releases found"
     if [ "$bump" = "true" ]; then
-      exit "--bump can't do its work when there are no existing release versions"
+      error "--bump can't do its work when there are no existing release versions"
     fi
   fi