make version tag prefix configurable so one can use it for github semver.org compliance
diff --git a/git-flow-support b/git-flow-support
index 61e19a7..d855eaa 100644
--- a/git-flow-support
+++ b/git-flow-support
@@ -17,8 +17,9 @@
 }
 
 parse_args() {
+	VERSION_PREFIX=$(git config --get gitflow.prefix.versiontag)
 	VERSION="$1"
-	BASE="${2:-${VERSION}}"
+	BASE="${2:-${VERSION_PREFIX}${VERSION}}"
 	if [ "$VERSION" = "" ]; then
 		echo "Missing argument <version>."
 		usage