make version tag prefix configurable so one can use it for github semver.org compliance
diff --git a/git-flow-release b/git-flow-release
index e1e2618..ff422e0 100644
--- a/git-flow-release
+++ b/git-flow-release
@@ -29,6 +29,7 @@
 }
 
 parse_args() {
+	VERSION_PREFIX=$(git config --get gitflow.prefix.versiontag)
 	VERSION="$1"
 	if [ "$VERSION" = "" ]; then
 		echo "Missing argument <version>."
@@ -82,7 +83,7 @@
 	# merge into master
 	git checkout $MASTER_BRANCH
 	git merge --no-ff $BRANCH
-	git tag $VERSION
+	git tag $VERSION_PREFIX$VERSION
 
 	# merge into develop
 	git checkout $DEVELOP_BRANCH